Glossary / L

Psychology terms starting with L

741 terms with short definitions. Study these as flashcards

L dataabbreviation: Information drawn from someone's life history or records helps describe their behavior and experiences.
L-alpha-acetyl-methadolnoun: A long-lasting opioid medication, also called LAAM, was used to reduce withdrawal symptoms during treatment for opioid dependence.
L-dopanoun: A medicine that the brain turns into dopamine to help reduce Parkinson's movement problems.
L-methylfolatenoun: An active form of vitamin B9 supports body functions and is sometimes used alongside medication in mental health treatment.
la belle indifférencephrase: A person shows surprisingly little concern about physical symptoms that appear serious or disabling.
LAAMabbreviation: This abbreviation stands for L-alpha-acetyl-methadol, an opioid medicine previously used to ease withdrawal, with effects lasting several days.
labeled linesnoun: Specialized nerve pathways are understood as carrying particular kinds of sensory information to the brain.
labeled-line theory of taste codingnoun: This theory proposes that each basic taste is signaled by activity in its own dedicated nerve pathway.
labelingnoun: Putting a person into a diagnosis category during assessment, which can sometimes oversimplify or mislead.
labeling theorynoun: A social theory proposes that labels and people's reactions to them can shape someone's identity and later behavior.
labianoun: Two pairs of skin folds form part of the vulva and surround the urinary and vaginal openings.
labialadjective: A speech sound has this quality when the lips help form it, as in p or f.
labileadjective: Describing emotions or mood that shift quickly and easily, often in response to small events.
labile affectnoun: A person's visible emotional expression changes quickly and markedly, sometimes shifting suddenly between very different emotions.
labio-prefix: This word part indicates that something involves the lips.
labiodentaladjective: A speech sound is formed by bringing the bottom lip against or close to the top teeth.
labornoun: Human work, especially the effort employees give to produce goods or provide services.
Labor Management Relations Actnoun: A 1947 federal law revised American labor rules, adding restrictions on unions and changing responsibilities in workplace bargaining.
labor relationsnoun: Workplace relationships between employers, employees, and unions involve negotiating pay, working conditions, and ways to settle disagreements.
labor turnovernoun: The departure of employees from an organization is measured over a specified period.
labor unionnoun: An organization represents workers collectively when negotiating with employers about pay, working conditions, and employment agreements.
laboratory researchphrase: Studies done in controlled settings let researchers change variables and better test cause and effect.
laboratory-method modelnoun: An educational approach uses social interaction to develop personal awareness and skills for relating to other people.
labyrinthnoun: An intricate inner-ear system of bony spaces and membrane-lined passages contains structures for hearing and balance.
labyrinthine sensenoun: A sense supported by the inner ear detects head movement and position, helping the body maintain balance.
labyrinthitisnoun: Inflammation within the inner ear can cause dizziness, difficulty balancing, and reduced hearing.
lacerationnoun: A wound has torn or cut tissue with uneven, ragged edges.
lack of fitnoun: A statistical model shows this mismatch when its predictions differ from what researchers actually observe.
lacrimal gland (lachrymal gland)noun: A gland near the upper outer corner of each eye produces tears and delivers them through small ducts.
lacrimal reflexnoun: Tears flow automatically when certain triggers stimulate sensory receptors, including irritation inside the nose.
lacrimationnoun: The eyes produce and release tears, sometimes in unusually large amounts.
lactate dehydrogenase (LDH)noun: An enzyme helps cells change lactate into pyruvate and reverse that change during energy processing.
lactationnoun: Making and releasing breast milk from the mammary glands after childbirth to feed an infant.
lacto-prefix: This word part adds a meaning connected with milk.
lactogenesisnoun: Hormonal changes start milk production in the mammary glands, including preparation during pregnancy and increased production after birth.
lactogenic hormonenoun: Another name for prolactin, this hormone supports milk production and also influences reproduction and some behaviors.
lactotrophnoun: A specialized cell in the front portion of the pituitary gland makes and releases prolactin.
lactotropic hormonenoun: Known also as prolactin, this hormone helps produce milk and participates in reproductive and behavioral processes.
lactotropinnoun: Also called prolactin, this pituitary hormone supports milk production and has additional roles in reproduction and behavior.
lacunanoun: A gap appears within something otherwise connected, such as a person's memory of an experience.
lacunar amnesianoun: Memory loss affects particular experiences or a limited period rather than a person's entire remembered life.
lacunar strokenoun: Blockage of a small artery deep inside the brain causes a small area of brain tissue to die.
LADabbreviation: An inborn mental system that helps children learn the rules of language quickly.
Ladd-Franklin theorynoun: A historical, superseded explanation proposed that light released substances from retinal molecules, producing experiences of different colors.
ladderingnoun: An interviewer repeatedly asks why answers matter to uncover connections between someone's choices, goals, beliefs, and values.
lagnoun: A short delay between stimulation and the body's response or conscious awareness.
lag effectnoun: During study, increasing the gap between repeated encounters with information can improve how well it is remembered later.
lagophthalmos (lagophthalmus)noun: One or both eyes remain partly uncovered because the eyelids do not meet when closing.
laissez-faire leadernoun: A leader gives little direction, rarely joins group activities, and usually offers input only when asked.
lallingnoun: Speech leaves out or replaces sounds, especially by using an L sound for sounds the speaker finds harder.
lalopathynoun: An older medical word describes any disorder affecting speech.
Lamarckismnoun: A historical evolutionary theory proposed that traits developed through use or disuse during life could pass to offspring.
Lamaze methodnoun: A childbirth preparation approach teaches what happens during birth and practices breathing, relaxation, massage, and support to manage discomfort.
lambdanoun: A Greek letter represents eigenvalues in lowercase or Wilks's statistic for testing combined group differences in uppercase.
lambda model (λ model)noun: A proposed movement model describes limb control through adjustments that set a balance point between opposing muscle groups.
Lambert’s lawnoun: For perpendicular light from a point source, doubling the distance reduces a surface's illumination to one quarter.
lamellipodiumnoun: A thin, broad extension spreads from a cell, including at the growing tip of a nerve cell.
laminar organizationnoun: Cells form distinct layers running roughly parallel to the surface in certain brain regions.
lamotriginenoun: A medicine used to help prevent bipolar depression episodes and some seizures, but not sudden mania.
LAMPabbreviation: A test program used to measure how well someone learns different kinds of information.
Land effectnoun: Combining differently filtered images can create a surprisingly rich range of perceived colors from limited light information.
Land theory of color visionnoun: The retinex theory proposes that vision determines colors by comparing relative light signals across different parts of a scene.
Landau reflexnoun: An infant held horizontally facing downward typically lifts the head and arches the back during part of the first year.
Landau–Kleffner syndromenoun: A rare childhood brain disorder causes loss of previously learned language skills alongside unusual electrical brain activity, often with seizures.
landmarknoun: A noticeable outside cue that helps someone build a mental map and find their way.
Landmark Forumnoun: A controversial group personal development program grew from Erhard's earlier training and aims to change participants' perspectives and behavior.
Landolt circlesnoun: Rings with small openings test sharpness of vision by asking people to identify where each gap lies.
landscaped officenoun: An open workplace groups people by communication needs and uses movable dividers to arrange flexible work areas.
Langdon Down’s diseasenoun: An outdated name describes Down syndrome, a genetic condition involving additional chromosome 21 material that influences development and health.
Langerhans cellsnoun: Specialized immune cells in the skin's outer layer detect foreign material and help activate immune responses.
languagenoun: A shared system of words, rules, and symbols used to communicate thoughts and feelings.
language acquisitionphrase: The way children learn to understand and use language, partly through inborn abilities and experience.
language acquisition device (LAD)phrase: An inborn mental system proposed to help children learn language from limited speech they hear.
language acquisition support system (LASS)noun: Bruner proposed that supportive exchanges with adults and older children help young children develop language.
language artsnoun: These school subjects teach students to communicate and understand messages through speech, written words, and careful listening.
language centernoun: A region of the brain's outer layer contributes to understanding or producing spoken or written language.
language contactnoun: Communities using different languages interact, allowing their languages to influence one another's words or patterns.
language deathnoun: A language stops having speakers, often after younger generations switch to another language.
language deficitnoun: A child's speech or language development is delayed, absent, or lost because of a neurological difficulty.
language delayphrase: When spoken words and sentences develop much later than usual, sometimes with and sometimes without a disorder.
language developmentphrase: Children gradually learn to understand and use words, grammar, and conversation as their thinking and social skills grow.
language disabilitynoun: A person has substantial difficulty developing or using language, affecting either particular skills or language more broadly.
language disorderphrase: A communication problem where someone has unusual trouble understanding or using spoken, written, or sign language.
language learning disability (LLD)noun: In this usage, children struggle to learn and use spoken language without another identified condition adequately explaining the difficulty.
language localizationnoun: Different parts of the brain make specialized contributions to understanding and producing spoken or written language.
language loyaltynoun: A community or its members strongly favor speaking their own language when it has minority status in society.
language maintenancenoun: Within immigrant or minority groups, younger generations continue speaking the language used by earlier generations.
language pathologyphrase: The field evaluates and treats problems with understanding, using, or producing spoken and written language.
language planningnoun: A government deliberately shapes a community's language use, including its public roles, vocabulary, spelling, or writing system.
language retardationnoun: An outdated label describes slower language development associated with neurological causes.
language shiftnoun: A community gradually replaces its traditional language with another, often the language spoken by the majority.
language socializationnoun: Children learn their family's and community's ways of communicating through everyday interactions.
language therapynoun: Professional support helps people improve their understanding, use, or production of language and speech.
language transfernoun: Patterns from a language someone already knows influence learning another language, sometimes helping and sometimes causing errors.
language universalnoun: A feature or rule is proposed to occur across all human languages, with some accounts allowing exceptions.
language-experience approachnoun: A reading method uses a child's spoken stories, written down by a teacher, as material for learning written words.
language-origin theorynoun: A proposed explanation addresses how language first emerged and developed in human history.
languishingnoun: A state of low mental well-being involves feeling empty, unmotivated, and disconnected from meaningful activities.
Lanterman Developmental Disabilities Actnoun: A California law establishes rights and organizes services and supports for people with developmental disabilities.
lapsus linguaenoun: An occasional speaking mistake occurs when someone unintentionally says a different sound or word than intended.
large-sample methodnoun: A statistical procedure estimates population values using approximations that improve when calculations include increasingly many observations.
Lariamnoun: A brand name identifies mefloquine, a malaria medicine that can also affect sleep, mood, and perception.
Larodopanoun: A brand name identifies levodopa, a medicine converted into dopamine and used to treat Parkinson's disease.
laryngeal framework surgerynoun: An operation reshapes voice box cartilage to adjust vocal fold position or tension and improve voice production.
laryngeal neoplasmnoun: An abnormal growth in the voice box may be cancerous or noncancerous and can interfere with speaking, swallowing, or breathing.
laryngeal paralysisnoun: Nerve damage prevents one or both vocal folds from moving normally, potentially affecting voice, swallowing, or breathing.
laryngeal reflexnoun: An automatic cough occurs when something irritates the voice box.
laryngectomynoun: An operation removes some or all voice box tissue, often as treatment for cancer.
laryngopharynxnoun: The lowest throat section sits behind the voice box and connects with the food pipe.
larynxnoun: The voice box sits above the windpipe and contains folds that vibrate to produce vocal sounds.
LASSabbreviation: Bruner's proposed language acquisition support system consists of adults and older children whose conversations support a young child's language learning.
Lasthénie de Ferjol syndromenoun: A historical syndrome label describes secretly producing one's own bleeding while presenting it as an unexplained illness.
LATabbreviation: Short for Lesch's alcoholism typology, this proposed system groups alcohol dependence into four patterns using symptoms and personal history.
latah (lattah)noun: A culturally patterned startle response, described especially in Malaysia and Indonesia, can include automatic imitation, speech, or obedience.
latchkey childrennoun: Children spend time at home after school without an adult present because their caregivers are working.
late bilingualismnoun: A person learns a second language after early childhood, although some definitions place the starting boundary at puberty.
late luteal phase dysphoric disordernoun: An older name describes premenstrual dysphoric disorder, involving disabling mood symptoms before menstruation that ease shortly after bleeding begins.
late paraphrenianoun: A historical diagnostic label describes a disorder involving delusions that first appears after age sixty.
late-onset schizophrenianoun: Schizophrenia first develops in middle adulthood or later, with the age boundary varying across definitions.
late-selection theorynoun: This account proposes that attention chooses which inputs receive further processing only after both noticed and unnoticed inputs undergo identification.
latency stagephrase: Between about ages 6 and puberty, sexual feelings quiet down while children focus on learning and same-sex friendships.
latent addition periodnoun: A very brief interval allows a second nerve stimulus to combine with effects still remaining from the first.
latent class analysis (LCA)noun: A statistical method estimates hidden groups from patterns across several measurements recorded as categories.
latent constructnoun: An unobserved concept is estimated from measurable signs and used to explain patterns in those signs.
latent contentnoun: The hidden unconscious meaning behind a dream or fantasy, often disguised to protect the person from anxiety.
latent factornoun: An underlying characteristic that cannot be measured directly is estimated from relationships among observable measurements.
latent goalnoun: An organization or program has an objective it does not publicly announce, though staff may recognize it.
latent homosexualitynoun: A historical label describes proposed same-sex attraction that someone has not expressed and may not recognize or acknowledge.
latent inhibitionnoun: Learning that a cue predicts something takes longer when previous encounters with that cue had no relevant consequence.
latent learningphrase: Knowledge picked up without trying can stay hidden until a reason appears to show it.
latent neednoun: A proposed need influences someone's behavior even though the person is unaware of having it.
latent stagenoun: Classical psychoanalysis proposes a childhood period when sexual interests become less prominent while learning and friendships gain attention.
latent structure analysisnoun: Statistical methods explain patterns among measured features by estimating underlying factors or groups that cannot be observed directly.
latent trait theorynoun: A measurement theory proposes that observable responses reflect underlying traits that can be estimated but cannot be observed directly.
latent variablephrase: An unseen trait is estimated from patterns in several measured behaviors or test responses.
later life adjustmentnoun: Older adults adapt to stresses and changes such as ongoing illness, losing loved ones, and new daily routines.
lateraladjective: Describing a career move to a different job at about the same level.
lateral bundlenoun: A group of nerve fibers toward the spinal cord's back and side carries signals about pain and temperature.
lateral cervical nucleusnoun: A small cluster of nerve cells in the upper spinal cord relays body sensation signals toward the brain.
lateral confusionnoun: A person favors different body sides for different activities or switches side preference during the same activity.
lateral corticospinal tractnoun: A major nerve pathway crosses in the lower brainstem and carries movement commands down the spinal cord, supporting precise limb movements.
lateral differencenoun: The brain's left and right halves differ in how much they contribute to particular behaviors or thinking abilities.
lateral dominancenoun: An older label describes one brain hemisphere contributing more than the other to a particular function, such as speech.
lateral fissurenoun: A deep groove on each brain hemisphere separates the temporal lobe below from the frontal and parietal lobes above.
lateral geniculate nucleus (LGN)noun: A paired structure within the thalamus receives retinal messages and forwards them to the brain’s main visual processing area.
lateral gyrusnoun: In historical brain descriptions, this name identifies a cortical ridge near the cingulate region above the major interhemispheric connection.
lateral hypothalamic syndromenoun: Experimental animals show four recovery stages after lateral hypothalamus damage, progressing from absent eating and drinking to altered habits.
lateral hypothalamus (LH)noun: An outer region of the hypothalamus helps regulate eating and other motivated behaviors.
lateral inhibitionnoun: Activity in nearby sensory pathways reduces a neuron's response, helping differences between neighboring signals stand out.
lateral lemniscusnoun: An ascending brainstem pathway carries hearing signals toward a midbrain processing center called the inferior colliculus.
lateral lispnoun: A speech pattern occurs when air escapes around the tongue's sides, changing sounds such as s and z.
lateral olfactory tractnoun: A bundle of nerve fibers carries smell signals from the olfactory bulb to other brain regions.
lateral posterior nucleusnoun: A cluster of thalamic neurons responds to visual information and contributes to distinguishing brightness levels.
lateral preoptic area (lPOA)noun: A region near the hypothalamus's front helps regulate sleep and reproductive responses to changing day length.
lateral rectusnoun: An eye muscle turns the eyeball outward, directing its gaze away from the nose.
lateral social comparisonnoun: People evaluate themselves against someone they consider roughly equal in the ability, situation, or quality being judged.
lateral specializationnoun: The brain's two hemispheres develop different strengths, with some functions relying more heavily on one side.
lateral spinothalamic tractnoun: An ascending nerve pathway carries mainly pain and temperature signals through the spinal cord toward the thalamus.
lateral sulcusnoun: A deep groove on each brain hemisphere separates the temporal lobe below from frontal and parietal regions above.
lateral thalamic nucleusnoun: A group of neurons occupies the outer portion of the thalamus, with functions depending on the particular subdivision.
lateral thinkingnoun: Creative problem solving involves deliberately questioning assumptions and trying a different perspective to discover fresh possibilities.
lateral ventriclenoun: Each brain hemisphere contains a chamber holding cerebrospinal fluid and connecting with the third ventricle.
lateral-line systemnoun: Many fish and some amphibians use specialized sensors to detect water movement along their bodies.
lateralitynoun: A person tends to favor one body side when performing particular activities, such as writing or kicking.
lateralizationnoun: Having one side of the body or brain used more for certain tasks than the other.
lateralized readiness potential (LRP)noun: An electrical brain measure compares motor activity across hemispheres to indicate preparation for a response using one hand.
lateropulsionnoun: An involuntary tendency to move or fall sideways can occur with certain nervous system disorders.
lateroventral nucleusnoun: A cell cluster within the thalamus passes cerebellar messages onward to movement-controlling cortex, supporting coordinated action.
Latin squarephrase: A within-subjects design that rotates treatment order so each condition appears equally often in each sequence position.
latitude of acceptancephrase: The set of opinion positions a person sees as acceptable, including the one they like best.
latitude of noncommitmentphrase: The range of opinions a person sees as neither acceptable nor objectionable.
latitude of rejectionphrase: In social judgment theory, the ideas about an issue that a person sees as unacceptable.
lattahnoun: A culturally described pattern, also spelled latah, involves unusually strong startle reactions, sometimes followed by automatic copying or obedience.
Latudanoun: A brand of lurasidone contains an atypical antipsychotic medicine used to treat schizophrenia.
laudanumnoun: An alcohol preparation containing opium was historically used to relieve pain and produce sedation.
laughing gasnoun: The gas nitrous oxide can reduce pain and produce lightheadedness or euphoria during medical use.
laughternoun: Sounds and breathing bursts that show amusement, but unusual laughing spells can signal some brain or mood disorders.
Launois–le Cleret syndromenoun: An older name for Fröhlich's syndrome describes increased body fat and delayed sexual development associated with hypothalamic or pituitary dysfunction.
Laurence–Moon–Bardet–Biedl syndromenoun: A historical diagnostic label combines inherited conditions involving worsening vision and variable differences in growth, movement, and intellectual development.
lawnoun: A general rule that describes a pattern found so reliably that no exceptions are expected.
law of advantagenoun: A proposed principle holds that, among competing responses, the more appealing or beneficial response happens more often.
law of assimilationnoun: A proposed learning principle states that unfamiliar situations tend to bring out responses already used in similar, familiar situations.
law of closurenoun: Perception tends to fill gaps in incomplete images or sounds so they seem like complete forms.
law of combinationnoun: A proposed principle says nearby cues can produce combined reactions, while one cue can bring out two reactions together.
law of common fatenoun: We tend to group objects together when they move in a shared direction or behave alike.
law of common regionnoun: People tend to visually group items when a surrounding border encloses them together.
law of constancynoun: Objects tend to look stable in properties such as size or brightness even when viewing conditions change.
law of contiguitynoun: Experiences that happen close together in place or time tend to become linked in memory.
law of continuitynoun: Vision tends to organize aligned elements into smooth paths rather than separate pieces with sudden changes of direction.
law of contrastnoun: A historical association principle proposes that experiencing or imagining something can bring its opposite to mind.
law of disusenoun: Thorndike's later abandoned proposal held that learned connections weaken when they are not used.
law of effectphrase: Behaviors followed by satisfying results become more likely to happen again in similar situations.
law of equalitynoun: A Gestalt principle proposes that figure parts seen as equal tend to be grouped into a whole.
law of equipotentialitynoun: A historical learning proposal claimed that any two stimuli could become associated with the same ease.
law of exercisephrase: Repeatedly doing a behavior makes you more likely to do that same behavior again later.
law of filial regressionnoun: Children of parents with extreme inherited traits tend, on average, to show less extreme values relative to the population.
law of forward conductionnoun: Nerve signals normally travel along an axon toward its endings, following the usual direction of neural communication.
law of frequencynoun: A traditional association principle proposes that repeatedly experiencing things together strengthens their connection in the mind.
law of good continuationnoun: Aligned visual elements tend to appear connected along a smooth course, even where lines cross or parts disappear.
law of good figurenoun: Vision tends to organize a pattern into the simplest coherent figure that its features allow.
law of good shapenoun: A Gestalt principle says we tend to see figures as regular and stable when their features permit.
law of inclusivenessnoun: A Gestalt principle proposes that a larger figure can dominate perception when it fully contains a smaller figure.
law of initial valuesnoun: A proposed physiological principle says a body's starting activity level influences how strongly it responds to a later stimulus.
law of large numbersnoun: With enough repeated observations under suitable conditions, their average approaches the expected average.
law of least actionnoun: A behavioral hypothesis proposes that organisms favor actions they expect will cost the least effort or energy.
law of mass actionnoun: Lashley's historical proposal held that learning problems depend more on how much cortex is damaged than where damage occurs.
law of neurobiotaxisnoun: A developmental principle proposes that growing neurons' receiving branches extend toward the sending fibers of nearby active neurons.
law of parsimonynoun: When explanations fit the evidence equally well, the one requiring fewer unsupported assumptions should be preferred.
law of Prägnanznoun: A Gestalt principle suggests that perception favors the simplest, clearest, most complete arrangement that the available information allows.
law of precisionnoun: A Gestalt principle proposes that perceived shapes tend toward regularity, symmetry, and clearly marked edges.
law of primacynoun: Information encountered first often has an advantage in learning, memory, or the formation of impressions.
law of prior entrynoun: When events happen together, an event receiving attention may seem to happen earlier than an unattended event.
law of proximitynoun: A Gestalt principle states that nearby objects tend to be perceived as belonging together.
law of recencynoun: Information encountered last often has an advantage in learning, memory, or judgments compared with earlier information.
law of similaritynoun: A principle of mental association proposes that experiencing or imagining something tends to bring similar things to mind.
law of specific nerve energiesnoun: The kind of sensation experienced depends on which sensory pathway is activated, rather than simply how it is stimulated.
law of sufficient reasonnoun: Leibniz proposed that anything existing must have an adequate reason explaining why it exists.
law of symmetrynoun: A Gestalt principle suggests that balanced, matching parts around a center tend to be seen as one whole.
law of usenoun: Thorndike's historical proposal claimed that repeatedly using a learned connection strengthens it, but he later abandoned this rule.
law-and-order orientationnoun: In Kohlberg's fourth stage, moral judgments emphasize respecting authority, fulfilling duties, and keeping society organized.
laws of groupingnoun: Gestalt principles describe how perception combines separate elements into organized wholes using features such as closeness, similarity, and shared movement.
laws of learningnoun: General principles describe conditions that influence learning, including consequences, repeated experiences, and the timing of events.
laws of thoughtnoun: Basic principles of logic are considered foundations for consistent reasoning, although thinkers disagree about which principles belong.
laxative addictionnoun: An older label describes dependence or felt reliance on medicines that help empty the bowels, sometimes involving eating disorders.
lay analysisnoun: Historically, this meant psychoanalytic treatment provided by a trained analyst who was not a medical doctor.
lay psychologynoun: In attribution theory, ordinary people use everyday reasoning to decide whether another person caused a particular action.
layperson personality theoriesnoun: People's everyday beliefs about which personality traits tend to occur together shape their impressions of others.
lazy eyenoun: Reduced vision develops when unusual visual input early in life interferes with the brain's learning to see clearly.
LBWabbreviation: The abbreviation means low birth weight, describing babies born weighing under 2,500 grams, regardless of pregnancy length.
LCAabbreviation: Latent class analysis is a statistical method that estimates hidden groups from patterns across several category-based measurements.
LCUabbreviation: A life-change unit assigns points to a life event according to its estimated potential to create stress.
LDabbreviation: A shortened label for learning disability, meaning ongoing trouble learning academic skills despite normal chances to learn.
LDHabbreviation: Lactate dehydrogenase names enzymes that help convert lactate into pyruvate and also carry out the reverse chemical change.
LEabbreviation: Lupus erythematosus is an illness in which immune activity mistakenly targets the body's tissues, causing inflammation.
lead-pipe rigiditynoun: Muscle stiffness creates even, continuous resistance when someone else moves a person's relaxed arm or leg.
leadernoun: A person who guides a group by organizing work, making decisions, and motivating others.
leader categorization theorynoun: This theory proposes that people automatically identify leaders by comparing individuals with their existing beliefs about typical leadership qualities.
leader matchnoun: Fiedler's training approach teaches leaders to assess and change work situations to fit their established leadership style.
leader prototypenoun: A mental picture represents the qualities someone expects a typical leader to have.
leader–member exchange theory (LMX theory)noun: This theory proposes that each leader's relationship with an individual member shapes that member's opportunities, resources, influence, and performance.
leaderless group discussionphrase: A hiring exercise where applicants discuss a topic without a named leader to show teamwork and leadership.
leaderless group therapynoun: Participants hold therapeutic group meetings without an assigned leader, either throughout treatment or alongside sessions guided by a therapist.
leadershipnoun: Guiding and motivating a group so people work together toward shared goals.
leadership emergencephrase: When a leaderless group comes to see one person as its leader, leadership emergence has occurred.
leadership labyrinthnoun: This metaphor captures how overlapping obstacles complicate progress toward leadership for women and people from minority groups.
leadership rolenoun: A group's guiding position carries expectations about directing tasks and managing relationships, whether the leader is formally appointed or informally recognized.
leadership stylephrase: A leader's usual way of directing a group, including how much they focus on tasks versus people.
leadership substitutenoun: A feature of the work, team, or organization reduces the need for someone to direct, support, or motivate members.
leadership theoriesphrase: Ideas explaining why leaders succeed or fail, based on traits, actions, situations, and followers' views.
leaf nodenoun: In a branching data structure, this endpoint has no further nodes below it as children.
leaf switchnoun: A flexible control activates with a small bend, helping people with limited movement operate devices.
leakagenoun: Unintended words or behavior reveal feelings or motives that differ from the message someone means to convey.
lean mediumnoun: A communication channel carries relatively few kinds of social information, as written messages lack vocal tone and facial expressions.
learned helplessnessphrase: After repeated uncontrollable stress, a person stops trying to change things even when help or options later appear.
learned optimismnoun: An acquired explanation style treats setbacks as caused by temporary, situation-specific factors outside oneself rather than lasting personal flaws.
learned responsephrase: A behavior formed through experience, such as a conditioned response learned after repeated pairings.
learned taste aversionnoun: A taste becomes disliked or avoided after being linked with feeling sick, sometimes following just one experience.
learned treatise exceptionnoun: A legal exception allows statements from authoritative scholarly publications to be used as evidence through expert testimony under certain conditions.
learningnoun: Gaining new knowledge, skills, or behaviors through experience, practice, or watching others, shown by lasting change.
Learning Abilities Measurement Program (LAMP)noun: A cognitive assessment program examines learning-related abilities, often to interpret the skills needed for particular jobs and tasks.
learning by doingnoun: Knowledge and skills develop through active participation in tasks and direct experience with their results.
learning centernoun: A classroom arrangement provides focused activities where students independently practice particular skills at a pace that suits them.
learning curvenoun: A graph tracks performance across time or practice attempts to show the course of learning.
learning difficultiesnoun: In some British usage, this label describes intellectual disability or specific disabilities affecting learning.
learning disabilities specialistnoun: A trained professional identifies students’ learning disabilities and helps arrange teaching and support suited to their needs.
learning disability (LD)noun: A brain-based problem causes school skills to be much weaker than expected for a person's age and intelligence.
learning disorder (LD)phrase: A brain-based problem that makes reading, math, or writing much harder than expected for someone's age and ability.
learning goalnoun: In Dweck’s theory, this aim centers on developing understanding or skill and mastering a task.
learning modelphrase: Views children as developing steadily by taking in what their environment teaches them.
learning paradigmphrase: A study setup that compares how different tasks affect unexpected later memory for the same material.
Learning Potential Assessment Device (LPAD)noun: This assessment explores how someone learns by giving feedback during tasks and examining their responses to that help.
learning setnoun: Repeatedly solving similar choice problems helps someone discover a general approach that makes later problems easier to learn.
learning skillsnoun: These abilities help people gain knowledge and deepen understanding through activities such as studying and classroom learning.
learning strategynoun: A chosen way of thinking or acting helps someone understand, remember, or practice new material.
learning stylenoun: A person’s usual approach to thinking, remembering, and solving problems can shape their preferences for learning activities.
learning support centernoun: An educational program or place offers extra help and personalized teaching to support students’ understanding and skills.
learning technologiesnoun: Electronic equipment and digital resources support teaching, practice, and access to learning materials.
learning theoryphrase: Ideas explaining how people and animals learn from experience, practice, rewards, and cues.
learning to learnphrase: Practice with changing examples of a similar task improves a person’s ability to learn later examples.
learning trialphrase: One chance to study or experience the material during a learning experiment.
learning typesnoun: People differ in how they prefer to organize, understand, and remember information, such as through words or pictures.
learning without awarenessnoun: Experience may change behavior without someone noticing the change, its cause, or the connection between them.
least effort principlenoun: This hypothesis proposes that people and other animals tend to choose actions that seem to demand the least energy.
least perceptible durationnoun: A comparison signal lasts just long enough or briefly enough to be noticeably different from a reference signal.
Least Preferred Coworker Scale (LPC Scale)phrase: This leadership test asks managers to rate their hardest coworker, showing whether they focus more on relationships or tasks.
least restrictive alternativenoun: This legal principle favors mental health care that meets safety and treatment needs while limiting personal freedom as little as possible.
least restrictive environment (LRE)noun: This educational principle supports teaching students with disabilities alongside peers without disabilities as far as their individual needs allow.
least significant difference (LSD)noun: Fisher’s procedure compares pairs of group averages after an overall statistical test indicates that some averages differ.
least squares criterionnoun: A statistical model is chosen to make the total of squared gaps between observations and predictions as small as possible.
least squares regressionphrase: Finds the line that makes overall squared prediction mistakes as small as possible.
leaving the fieldphrase: Someone withdraws physically or mentally from a situation because its obstacles or conflicts seem impossible to resolve.
Leber’s diseasenoun: An inherited disorder damages the optic nerves and reduces central vision, often beginning in young adulthood.
Leboyer techniquenoun: This childbirth approach aims to ease a newborn’s transition using quiet surroundings, soft lighting, close contact, and a warm bath.
lecanomancynoun: This divination practice claims to reveal future events through images or patterns seen in water held in a container.
Lectopamnoun: This brand name identifies bromazepam, a benzodiazepine medicine used to reduce anxiety.
lecture methodnoun: An instructor teaches a group by giving an organized spoken presentation of information.
Lee–Boot effectnoun: Among female mice housed together, chemical signals can lengthen the inactive phase of the reproductive cycle.
left brainphrase: The brain hemisphere that usually handles language and many analytic tasks.
left censoringnoun: Researchers know an event happened before observation began but cannot determine exactly when it happened.
left hemispherephrase: The brain's left half helps control movement, process sensations, and in most people handles language more strongly.
left-handednessnoun: A person usually favors their left hand for everyday tasks requiring skill, such as writing or throwing.
left-hemisphere consciousnessnoun: Gazzaniga proposed that consciousness is located in the brain’s usually language-dominant left half, a claim other researchers have challenged.
legal blindnessnoun: A legal classification identifies severe vision loss using set limits for corrected visual sharpness or the extent of visible space.
legal capacityphrase: Having enough understanding to make reasonable choices in legal matters, such as contracts, wills, or trial decisions.
legal psychiatrynoun: This medical specialty applies knowledge of mental disorders to legal questions, including decision-making ability and responsibility for actions.
legal psychologynoun: Psychological research and practice help address questions within civil and criminal justice, including witness memory and psychological assessment.
legal testimonyphrase: Statements a person gives in court under oath, spoken or written, to provide evidence.
legasthenianoun: This disputed syndrome involves trouble assembling words from letters and identifying their letters despite otherwise adequate thinking and perception.
legendnoun: A traditional story travels across generations and may mix historical events with details added through retelling.
legibilitynoun: A place has this quality when its layout and landmarks make it easy to understand mentally and navigate.
legitimate authoritynoun: Someone can direct or influence others because they hold an official position recognized by law.
legitimate powerphrase: Influence comes from a person's role in a group because others accept that role's right to give orders.
leisure lifestylenoun: A person organizes much of life around freely chosen activities, with fewer duties such as paid work.
Lejeune syndromenoun: Missing genetic material from chromosome 5 causes developmental differences, often including intellectual disability and a distinctive high-pitched infant cry.
lek matingnoun: Males gather in a shared display area, where females compare their performances and choose mates.
lemmanoun: In linguistics, a dictionary headword represents a word together with its grammatical variations, such as different tenses.
lemniscal systemnoun: Ascending nerve pathways carry sensory information, including touch and sound, toward relay centers higher in the brain.
length of stay (LOS)phrase: How many days a patient stays in a hospital during one uninterrupted admission.
leniency errornoun: A rater repeatedly gives overly favorable evaluations because they overlook weaknesses or apply standards too loosely.
lensnoun: A way of looking at information that shapes what you notice and how you understand it.
lens modelnoun: Brunswik’s model explains judgments as interpretations built from selected clues, with some clues given more importance than others.
lenticular nucleusnoun: A deep brain grouping consists of the putamen alongside the globus pallidus and helps regulate movements made on purpose.
Leonardo’s paradoxnoun: Straight features can appear curved near the edges of a wide view that contains lines converging with distance.
leptinnoun: Fat cells release this hormone, which signals stored energy to the brain and helps regulate appetite.
leptokurticadjective: Describes a score distribution with a taller center and thinner ends than a normal curve.
leptomorphnoun: Eysenck’s historical body-build classification used this label for a relatively narrow physique identified by height compared with chest width.
leptosome typenoun: Kretschmer’s historical classification described a slender, long-limbed body with a narrow chest and proposed links to temperament.
LEQabbreviation: The Lifetime of Experiences Questionnaire surveys older adults’ past and present mentally engaging activities to estimate cognitive reserve.
LESabbreviation: A temporary increase in activity in a small brain area that makes nearby neurons more likely to fire.
lesbian feminismnoun: This feminist perspective centers lesbian experiences and understands lesbian relationships as potentially challenging men’s social dominance and supporting women’s autonomy.
lesbian separatismnoun: A radical lesbian feminist position advocates rejecting heterosexual relationships and separating from institutions organized around men's power.
lesbianismnoun: This older word describes women's attraction to other women or sexual intimacy with them.
Lesch–Nyhan syndromenoun: An inherited enzyme deficiency causes excess uric acid, movement difficulties, cognitive challenges, and often compulsive self-injury.
Lesch’s alcoholism typology (LAT)noun: A proposed classification divides alcohol dependence into four patterns involving withdrawal, emotional difficulties, mood problems, or neurological and developmental histories.
lesionnoun: Damage to body tissue or an organ caused by injury, disease, or surgery.
less-is-more hypothesisnoun: A proposal suggests young children's limited mental processing capacity may simplify language input and help them learn grammar.
lethal catatonianoun: A historical description identifies an extreme state of agitation and confusion that can progress to death.
lethal dose (LD)noun: An amount of a substance sufficient to cause death depends on the organism and conditions of exposure.
lethalitynoun: How likely an action or method is to cause death.
lethality scalenoun: A structured rating tool combines information about a person to estimate the risk of suicidal behavior.
lethargynoun: Very low energy and little drive to act, often seen in depression and some medical conditions.
letter cancellation testnoun: An assessment measures attention and visual movement coordination by asking someone to mark target letters among distracting letters.
letter-by-letter readingnoun: A person recognizes a written word by identifying its letters one at a time and combining them.
Letter–Number Sequencingnoun: A working memory task requires repeating mixed spoken symbols with numbers ordered numerically first and letters alphabetically afterward.
letting gophrase: During dying, a person may stop struggling to stay alive after prolonged effort and suffering.
leuco- (leuc-; leuko-; leuk-)prefix: A word part placed before another element indicates whiteness or lack of color.
leukocyte (leucocyte)noun: A white blood cell helps the immune system respond to infections and other foreign material.
leukotomy (leucotomy)noun: A historical brain operation cut connections involving the frontal lobes in attempts to treat severe mental health conditions.
leuprolidenoun: A medicine mimics gonadotropin-releasing hormone and, with continued use, reduces production of testosterone or estrogen.
levelnoun: Each specific amount or category of an independent variable in a study.
Level I–Level II theorynoun: A proposed hierarchy separates basic association learning and brief memory from more complex abilities such as reasoning and categorizing.
level of analysisnoun: The chosen scope of an explanation determines whether researchers examine individuals, groups, organizations, or wider society.
level of measurementnoun: The kind of measurement scale used determines how much detail scores provide and which comparisons they support.
level of significancephrase: The cutoff probability, often alpha, used to decide if results are unlikely by chance alone.
level-of-aspiration theorynoun: A theory proposes that people's initial goals shape their performance and their emotional and behavioral responses to results.
levels of consciousnessnoun: Different degrees of wakefulness and awareness range from being fully alert to sleep or severely reduced consciousness.
levels of intelligencephrase: A way of organizing intelligence from broad overall ability at the top to narrow specific skills below.
levels-of-processing model of memorynoun: A theory proposes that thinking about information's meaning generally creates stronger memories than noticing its appearance or sound.
Levene test for equality of variancenoun: A statistical test evaluates whether score variability differs across the groups being compared.
lever switchnoun: An electrical control uses a movable arm that can help people operate devices with limited precise hand movement.
Levinson’s adult development theorynoun: A proposed model describes early, middle, and later adulthood as alternating periods of transition and relative stability.
levitationnoun: An alleged paranormal event involves a person or object rising and hovering without an apparent physical explanation.
Levo-Dromorannoun: A trade name identifies levorphanol, an opioid pain medicine that can cause dependence and slow breathing.
levodopa (L-dopa)noun: A medicine that the brain turns into dopamine, often used to ease Parkinson's movement problems.
levomepromazinenoun: Another name for methotrimeprazine identifies a phenothiazine antipsychotic medicine also used to relieve pain.
Levopromenoun: This brand name identifies methotrimeprazine, a medicine with antipsychotic and pain-relieving effects.
levorphanolnoun: An opioid medicine reduces pain but can also cause dependence and dangerously slow breathing.
Lewy body dementiaphrase: A dementia causing early hallucinations, changing alertness, and Parkinson-like movement problems from protein clumps in the brain.
lexical accessnoun: The mind retrieves stored word knowledge to produce a word or recognize one encountered in language.
lexical agraphianoun: A writing impairment particularly disrupts spelling words with unusual or uncertain spellings while preserving spelling based on sound.
lexical ambiguitynoun: A single word allows different interpretations because it carries multiple meanings.
lexical decisionnoun: A research task asks people to judge whether letter combinations form real words, often while response speed is recorded.
lexical hypothesisphrase: Important personality differences tend to get named in everyday language because people notice and talk about them often.
lexical memorynoun: A person's stored vocabulary includes words they can produce and words they recognize or understand.
lexical wordnoun: A word carries meaning about things, actions, qualities, or ideas beyond its grammatical role in a sentence.
lexical-selection rulesnoun: Language rules limit which words can fit particular grammatical structures, based on each word's grammatical properties.
lexical–gustatory synesthesianoun: Certain words automatically trigger consistent taste experiences, such as a particular flavor when the word is heard.
lexicologynoun: A branch of language study examines word meanings and how words relate to each other.
lexiconnoun: A language's collection of words, or an individual's knowledge of words, forms its vocabulary.
LFAabbreviation: An outdated label, low-functioning autism, grouped autistic people by lower measured intelligence and greater difficulties with daily activities.
LGBTQabbreviation: An inclusive label for people with diverse sexual orientations and gender identities, including lesbian, gay, bisexual, and transgender people.
LGNabbreviation: The lateral geniculate nucleus is a thalamic structure that passes visual signals from the retina toward the visual cortex.
LHabbreviation: This abbreviation can mean lateral hypothalamus, a brain region involved in eating, or luteinizing hormone, which regulates reproductive functions.
liabilitynoun: Legal responsibility to pay money for harm a court says you caused someone.
liberalismnoun: An attitude welcomes different ways of thinking or behaving and may support changes to established customs.
liberation psychologynoun: A movement originating in South America uses psychology to challenge poverty, oppression, and injustice alongside affected communities.
libidinal developmentnoun: Freud's theory proposes that sexual energy shifts focus across childhood stages and helps shape personality.
libidinal stagenoun: Within Freud's developmental theory, each proposed period centers sexual energy on particular bodily interests or patterns.
libidinal transferencenoun: Psychoanalytic theory proposes that love or sexual feelings associated with earlier important people become directed toward the therapist.
libidinal typesnoun: Freud proposed personality categories based on whether sexual energy mainly serves attachment, conscience, or self-preservation.
libidinizationnoun: In psychoanalytic language, a body area, function, interest, or activity becomes associated with sexual pleasure.
libidonoun: A person's level of sexual desire or drive.
libido-binding activitynoun: In historical group therapy, a shared task was proposed to channel sexual energy into an interest without increasing sexual excitement.
Libriumnoun: A brand name for chlordiazepoxide, this benzodiazepine medicine reduces anxiety and is also used to manage alcohol withdrawal.
licensenoun: Official government permission to do a job, based on education, exams, or both.
licensed practical nurse (LPN)noun: A nursing professional completes an approved practical nursing program and receives a license to provide care within an authorized scope.
licking behaviornoun: An animal uses its tongue on itself or another animal, often during grooming or care of its young.
lickometernoun: A research device counts an animal's tongue contacts with a drinking tube to measure licking during drinking.
lid apraxianoun: A person has difficulty deliberately closing their eyes because control of the intended eyelid movement is impaired.
lienoun: A knowingly false statement or act meant to make another person believe something untrue.
lie detectornoun: A machine that tracks body changes during questioning, but it cannot reliably prove someone is lying.
lie scalenoun: A group of assessment questions checks for response patterns suggesting dishonesty or an effort to appear unusually good.
Liebmann effectnoun: Neighboring visual areas may seem to blend together when their boundary depends on color differences alone, without brightness differences.
life coachingnoun: A coach provides guidance and encouragement to help people choose and pursue meaningful goals in work or personal life.
life crisisnoun: A major personal event creates a period of distress that requires substantial adjustment and may affect mental or physical health.
life cyclenoun: An organism develops through a repeating sequence that connects one generation's starting stage with the equivalent stage in its offspring.
life eventsphrase: Major experiences across life, expected or unexpected, that can shape development, personality, and stress.
Life Events Rating Scalenoun: A questionnaire assigns weighted points to major life events to estimate the overall adjustment and potential stress they involve.
life expectancyphrase: The average number of years people in a group are expected to live.
life forcenoun: In Bergson's philosophy, a proposed special energy gives organisms life and directs evolution toward an end.
life goalnoun: In Adler's theory, a person's imagined attainable future helps guide efforts to overcome actual or perceived feelings of inadequacy.
life historyphrase: A client's organized story from birth to now, covering important emotional, social, and thinking development.
life instinctnoun: Freud proposed a basic drive combining efforts to stay alive with sexual motivations supporting the continuation of life.
life lienoun: Adler proposed that falsely blaming unavoidable failure on others or circumstances can help a person avoid responsibility.
life plannoun: In Adler's theory, a person's characteristic approach to living and guiding beliefs organize their pursuit of an imagined future goal.
life reviewnoun: A person thoughtfully examines earlier experiences to understand their meaning, often during older adulthood or as part of therapy.
life rhythmnoun: A living organism shows recurring changes in bodily or mental activity, sometimes linked to daily or seasonal environmental patterns.
life satisfactionnoun: How much a person feels their life is good, meaningful, and satisfying overall.
life spacenoun: In Lewin's theory, a person's current needs, surroundings, relationships, and perceived possibilities together form the situation shaping their behavior.
life stressphrase: Strong pressure caused by major upsetting events, such as divorce, job loss, or death of someone close.
life tablenoun: A statistical chart shows a population's chances of surviving or dying at different ages, helping researchers estimate expected lifespan.
life-change unit (LCU)noun: A scoring point represents how much adjustment a major life event typically requires, helping researchers estimate its potential stress.
life-history methodnoun: A structured interview gathers important events from someone's past to help assess how they are functioning now.
life-space interviewnoun: Treatment staff talk with a child during or soon after distress, using the immediate experience to support understanding and coping.
lifelinenoun: In therapy, a person draws past and expected events along a line, marking feelings and changes in how life is going.
lifespannoun: The total length of a person's life, from birth until death.
lifespan contextualismnoun: This developmental view sees people as shaped by their social surroundings while also actively shaping their own development throughout life.
lifespan developmental psychologynoun: Researchers study changes in thinking, feeling, and behavior throughout life, considering interacting influences beyond age alone.
lifespan epidemiological personality approachnoun: This approach studies health by connecting personality, biology, social surroundings, and a person's past, present, and expected future.
lifespan perspectivenoun: Human development continues throughout life, with gains and losses across different abilities and ongoing capacity for change.
lifestylenoun: A person's usual pattern of living, shown in daily habits, attitudes, interests, and choices.
lifestyle modificationnoun: A person deliberately adjusts everyday habits or routines to support health, manage a condition, or lower the chance of illness.
Lifetime of Experiences Questionnaire (LEQ)noun: A questionnaire surveys older adults' mentally engaging activities across life to estimate resources that may help thinking withstand brain changes.
lifetime personalitynoun: In Murray's personality theory, a person's most characteristic pattern of behavior is considered across their entire life.
lifetime risknoun: An estimate describes the chance that someone will receive a particular diagnosis over the course of their life.
ligandnoun: A molecule attaches to a particular binding spot on another molecule, such as a receptor involved in cell signaling.
ligand-gated ion channelnoun: A protein passage through a cell membrane changes its opening when a chemical binds, controlling the movement of charged particles.
light adaptationnoun: The visual system adjusts to brighter surroundings by reducing light sensitivity, with pupil narrowing and greater reliance on cone cells.
light cellnoun: A Type II taste cell appears pale under an electron microscope and samples chemicals entering the taste bud's opening.
light inductionnoun: Stimulation in one visual area changes the appearance of a neighboring area, such as how its color looks.
light pointernoun: A light attached to a head-mounted stick lets a person activate compatible assistive equipment through head movements.
light reflexnoun: The pupil automatically becomes smaller in brighter surroundings and larger in dimmer surroundings, adjusting how much light enters.
light sensitivityphrase: Bright light causes eye pain or discomfort and makes a person want dimmer surroundings.
light therapynoun: Controlled exposure to specially provided light is used to treat certain conditions, including seasonal depression with bright visible light.
light trancenoun: In traditional hypnosis descriptions, a mild hypnotic state involves responsiveness to suggestions, such as difficulty opening the eyes.
light–dark cyclenoun: Researchers use a repeating schedule of illuminated and dark periods in animal housing to control exposure to light.
lightness constancynoun: An object's surface tends to look similarly light or dark even when the amount of light falling on it changes.
lightness contrastnoun: A surface can appear lighter beside a dark area and darker beside a light area, exaggerating their apparent difference.
lightning calculatornoun: A person performs numerical calculations mentally at an unusually fast speed, showing a highly developed ability in this particular area.
likelihoodnoun: How probable certain results are if the population assumptions are true.
likelihood functionphrase: Shows how well different population values could have produced the sample data you observed.
likelihood principlenoun: Helmholtz proposed that people tend to see the interpretation of visual information that is most likely to be correct.
likelihood ratio (LR)noun: A number compares two hypotheses by dividing the likelihood of the observed data under one by that under the other.
Likert scalenoun: A rating format where people choose from ordered options, like strongly disagree to strongly agree, to show attitude strength.
liking scalenoun: A questionnaire measures how positively someone views another person and how much they want to spend time with them.
Lilliputian hallucinationnoun: A person sees people, animals, or objects that are not actually present and that appear unusually tiny.
limb kinetic apraxianoun: A movement difficulty makes precise, separate finger actions hard despite having enough strength and understanding the task.
limbic cortexnoun: Certain parts of the brain's outer layer, especially the cingulate cortex, belong to networks supporting emotion and memory.
limbic epilepsynoun: A neurological condition causes repeated seizures that begin in brain regions involved in memory and emotion.
limbic lobenoun: A sometimes distinguished brain division includes the cingulate cortex, the parahippocampal gyrus, and structures forming the hippocampal region.
limbic systemnoun: A linked group of brain areas that helps control emotion, memory, learning, and body responses.
Limbitrolnoun: A brand-name medicine combines amitriptyline with chlordiazepoxide to treat depression accompanied by anxiety.
limennoun: A threshold marks the stimulus strength needed for detection or a response, often measured at 50% detection.
limerencenoun: An intense romantic preoccupation involves longing for someone and strong sensitivity to whether that person returns your feelings.
liminaladjective: Something described this way concerns the boundary at which a sensation becomes detectable.
limited competencynoun: A court determines that someone can manage certain activities independently but needs a guardian's assistance with others.
limited guardianshipnoun: A legal arrangement gives a guardian authority over specified areas while leaving other decisions with the individual.
limited holdnoun: A reinforcement rule allows a response to earn reinforcement only within a set window after it becomes available.
limited responsibilitynoun: A legal defense uses evidence about a person's mental condition to argue for reduced accountability for an offense.
limited-capacity systemnoun: A model describes working memory or attention as having restricted resources for holding or processing information at once.
limophthisisnoun: An older term describes bodily and mental effects of extreme weight loss caused by severe lack of nourishment.
Limulidaenoun: This animal family includes horseshoe crabs, whose large eye neurons help researchers study how vision works.
line graphnoun: A chart joins measurement points with straight segments to show patterns, often across time.
line managementnoun: A workplace structure gives each manager authority over direct reports and responsibility to the manager above.
line of beautynoun: An S-shaped curve was proposed by painter William Hogarth as the shape with the greatest beauty.
line of fixationnoun: An imagined straight path connects the object you focus on with the fovea, the retinal center for sharp vision.
line of regardnoun: An imagined straight path connects a viewed object with the point around which the eye rotates.
line spectrumnoun: A frequency display shows a repeating sound's components as separate lines at specific frequencies.
linearadjective: Shows a relationship where one variable changes at a steady rate with another.
linear causationnoun: A simple causal pattern runs from one cause to an effect, directly or through a straightforward sequence.
linear correlationphrase: Shows how strongly two things change together in a straight-line pattern when graphed.
linear modelnoun: A statistical model estimates an outcome by adding predictor terms multiplied by adjustable weights, usually with a starting constant.
linear perspectivephrase: A one-eye depth cue where parallel lines seem to come together as they get farther away.
linear programnoun: A self-study lesson presents small steps in a fixed sequence, with questions and immediate answer feedback.
linear regressionphrase: A method for predicting one score from others when their relationship follows a straight-line pattern.
linear relationshipphrase: Two variables change together at a steady rate, so their points would line up straight.
linear systemnoun: A system adds its separate input responses together and scales its output proportionally when the input is scaled.
linear transformationphrase: Changing scores by adding, subtracting, multiplying, or dividing by constants while keeping their order and spacing pattern.
linear typenoun: A historical body classification describes a slender build with a narrow chest, long neck, and long nose.
linearizingnoun: In this usage, data values are rescaled by multiplying by a constant and adding another constant.
lineupnoun: An eyewitness views several people together or one after another and indicates whether anyone is recognized as the offender.
lingering trajectorynoun: A pattern of dying involves a prolonged decline during terminal illness, often with limited attempts at aggressive treatment.
lingua francanoun: A shared language lets people communicate when they grew up speaking different languages.
lingualadjective: Something described this way concerns the tongue, speech, or language.
lingual frenulumnoun: A small tissue fold beneath the tongue connects it to the mouth's floor and helps limit its movement.
lingual glandnoun: A gland in the tongue releases fluid thought to help move dissolved taste substances among taste cells.
lingual gyrusnoun: A fold toward the brain's lower back surface helps process visual information and has been linked to dreaming.
lingual nervenoun: This trigeminal branch carries touch, temperature, and pain signals from the tongue’s forward two-thirds and nearby tissues toward the brain.
lingual papillanoun: A small projection on the tongue belongs to one of four types, some containing taste buds.
linguistnoun: A researcher studies language, including its structure, use, development, or the features of particular languages.
linguistic approachnoun: This reading method connects familiar speech to print by teaching letter–sound relationships within meaningful, regularly spelled words.
linguistic awarenessnoun: The ability to think consciously about language includes noticing its structure, meanings, and uses.
linguistic determinismnoun: A disputed hypothesis proposes that the language people speak determines the categories they can use in thought.
linguistic intergroup biasnoun: People use broad descriptions for their group's positive acts and other groups' negative acts, and specific descriptions for the reverse.
linguistic minoritynoun: A community within a society has a native language spoken by a smaller share of that society's population.
linguistic relativityphrase: Different languages divide up meanings in different ways, such as using separate words for kinds of water.
linguistic typologynoun: An approach groups languages according to shared structural features, such as their usual word order.
linguistic universalnoun: A feature or structural rule is proposed to occur across all human languages, with some formulations allowing exceptions.
linguistic–kinesic methodnoun: An observational method examines psychological disturbance through people's language and bodily movements during interactions.
linguisticsnoun: A scientific field investigates how human language is structured, produced, understood, used socially, and changed over time.
link analysisnoun: An ergonomic method studies work sequences and movements of people or objects to improve workplace design, efficiency, and safety.
linking verbnoun: A verb connects a sentence's subject with words that identify or describe that subject.
Lioresalnoun: A brand name identifies baclofen, a medicine that reduces excessive muscle tightness by acting on GABA-B receptors.
liothyroninenoun: A manufactured thyroid hormone treats hormone deficiency and is sometimes added to antidepressants when depression has not improved enough.
lip bitingnoun: Repeatedly biting one's lips can be a habit linked to nervousness or part of a medical condition.
lip eroticismnoun: Sexual excitement or pleasure comes from activities involving the lips.
lip pursingnoun: A protruding, tightly gathered lip posture has historically been described as a possible sign of catatonia.
lipid-metabolism disordersnoun: Conditions that disrupt how the body handles fats can produce abnormal fat levels and sometimes affect brain development.
lipodystrophynoun: Abnormal loss or distribution of body fat can affect particular areas or nearly the entire body.
lipostatic hypothesisnoun: A proposed explanation links long-term eating regulation to body fat, with this version emphasizing circulating fatty acids.
lipotrophic diabetes mellitusnoun: This older label describes diabetes-associated loss of fat beneath the skin at sites where insulin has been injected.
Lipps illusion theorynoun: A historical proposal suggested that an observer's emotions produce the visual distortions experienced in illusions.
lipreadingnoun: Understanding speech by watching mouth movements can help communication, although many speech sounds look alike.
liquidadjective: Describing speech sounds like l or r, made with smooth airflow and only a small blockage in the mouth.
liquidation of attachmentnoun: Pierre Janet described a therapeutic process of loosening emotional ties that keep someone bound to a painful situation.
lisdexamfetaminenoun: A stimulant medicine used to treat ADHD that becomes active after the body changes it.
LISPabbreviation: Short for list processing, this programming language organizes information in lists and has supported artificial intelligence research.
lissencephalynoun: Unusual movement of developing nerve cells leaves the brain's surface with fewer normal folds, often causing serious developmental difficulties.
listeningnoun: Carefully paying attention to a client's words, actions, and intended meanings during counseling or research.
listening attitudenoun: In therapy, a person remains open to understanding a client's experiences or exploring their own experiences.
listening strategynoun: Listeners tend to give greater attention to a talk's opening and closing than to its middle.
listwise deletionnoun: Researchers exclude a person's entire record from an analysis when any measurement needed for that analysis is missing.
literacynoun: Being able to understand written words and put thoughts into writing in a language.
literacy testnoun: An assessment measures someone's reading and writing skills or their understanding of literature.
literal alexianoun: Neurological damage or disorder makes recognizing individual written letters or numerals difficult or impossible.
literal paraphasianoun: A speech disturbance changes intended words by replacing, rearranging, leaving out, or adding speech sounds.
literal replicationnoun: Researchers repeat a study using procedures matched as closely as possible to check whether its findings occur again.
literalismnoun: A person sticks to directly observable facts or the explicit wording of a statement, rather than interpreting beyond them.
lithiumnoun: A mood-stabilizing medicine used mainly for bipolar disorder, with blood checks needed because toxic means poisonous.
litigious paranoianoun: A historical psychiatric label described persistent legal complaints driven by exaggerated or unfounded beliefs about persecution or violated rights.
Little Albertphrase: A young boy in Watson's study showed that fear can be classically conditioned in humans.
Little Hansnoun: Freud's 1909 case study interpreted a young boy's fear of horses through proposed unconscious conflicts involving his parents.
living willnoun: A legal document records treatment wishes for a future time when someone cannot make or communicate health care decisions.
LLDabbreviation: Language learning disability describes difficulties developing spoken language skills that are not explained by another identified condition.
Lloyd Morgan’s canonnoun: A guiding principle favors simpler psychological explanations of animal behavior when they adequately account for what is observed.
LLRabbreviation: The log-likelihood ratio compares two models by taking the logarithm of the ratio of their likelihoods for observed data.
LMX theoryabbreviation: A leadership idea that bosses build different-quality relationships with workers, shaping trust, support, and job outcomes.
LNNBabbreviation: This collection of structured tests measures mental skills, movement, and perception to help assess how someone's brain functions.
lobenoun: A rounded section of the brain separated from nearby areas by clear grooves or boundaries.
lobectomynoun: Surgical removal of all or part of a brain lobe, often to help control seizures.
lobotomynoun: A historical psychiatric operation severed connections involving the brain's frontal regions and could cause lasting, serious changes in functioning.
LOCabbreviation: Loss of consciousness means a person becomes unaware of surrounding events and loses the ability to respond voluntarily.
local circuitnoun: A connected group of nerve cells processes signals within a particular brain region and level of organization.
local circuit neuronnoun: A nerve cell has short branches that connect mainly with nearby cells rather than distant brain regions.
local enhancementnoun: Watching others act in a place draws an observer's attention there, making learning through their own exploration more likely.
local excitatory state (LES)noun: A weak stimulus creates a nearby electrical change that briefly makes a nerve cell easier to activate without triggering an impulse.
local independencenoun: A statistical model assumes measurements are independent once the hidden factors explaining their shared patterns are taken into account.
local potentialnoun: A nearby change in a nerve cell's voltage weakens with distance and may trigger an impulse if it reaches threshold.
local regression (loess; lowess)noun: A statistical method builds a smooth trend by fitting simple curves around individual points, giving nearby observations greater weight.
local–global distinctionnoun: Perception can focus on an overall shape or on the smaller elements that together create that shape.
localizationnoun: Knowing where a sensed thing is in space, no matter which sense detects it.
localization of functionnoun: Certain regions within the brain's outer layer contribute more strongly than others to particular thinking skills and behaviors.
localized amnesiaphrase: Memory loss limited to certain events or a specific period, often after trauma.
location constancynoun: An unmoving object appears to stay in the same place even as the viewer changes position.
location-invariant neuronnoun: A visual nerve cell responds to a particular stimulus across different positions within the area it monitors.
locinoun: Places in an imagined route that help you store and later recall information.
loci methodnoun: A memory technique links imagined items to places along a familiar route, which can later guide recall.
lock-and-key theorynoun: A proposed explanation of smell suggests that odor molecules activate receptors through a fit involving their shapes.
Locke’s theory of goal settingnoun: A theory proposes that accepted, specific, challenging goals improve performance by directing attention, effort, persistence, and strategies, supported by feedback.
locked wardnoun: A hospital unit provides psychiatric care behind secured doors, with staff controlling entry and exit.
locked-in syndromenoun: A person remains conscious but cannot speak or move most muscles, often retaining eye movements for communication.
Lockhart v. McCreenoun: In 1986, America's highest court upheld screening potential jurors for their ability to consider a legally permitted death sentence.
lockoutnoun: An employer blocks workers from working during labor talks until they accept the employer's contract terms.
loco plantnoun: Certain Astragalus or Oxytropis plants contain toxins that can disrupt nerve function, movement, and perception when eaten.
locomotionnoun: An organism changes its location through actions such as walking, crawling, swimming, or flying.
locomotor arrestnoun: Movement stops or is suppressed through voluntary control, a drug's effects, or stimulation of certain brain structures.
locomotor ataxianoun: Damage to sensory pathways in the spinal cord from neurosyphilis causes severe difficulty coordinating walking.
locomotor playnoun: Vigorous physical play uses repeated, exaggerated movements, including running after others, scrambling upward, or playful tumbling.
locuranoun: Some Latino communities use this cultural concept for severe distress involving confused communication, unusual perceptions, and disrupted daily functioning.
locusnoun: A specific location where something is found, such as a body problem or a gene's spot.
locus ceruleus (locus coeruleus; locus caeruleus)noun: A small brainstem cell group releases norepinephrine, helping regulate alertness and possibly contributing to anxiety.
locus of causalitynoun: An explanation places an event's cause either within oneself or in circumstances outside oneself.
locus of controlphrase: A person's usual belief about whether life outcomes come mostly from their own actions or from outside forces.
locus of stabilitynoun: An explanation treats an event's cause as either lasting over time or likely to change.
locutionary actnoun: Producing a meaningful spoken expression is the basic speaking act distinguished from its purpose or effect.
LOD scorenoun: A logarithmic score compares genetic evidence for linkage between chromosome sites against evidence that they are inherited independently.
loessnoun: A statistical method builds a smooth curve by fitting small sections of data while giving nearby observations greater weight.
log likelihoodnoun: Taking the logarithm of a model's likelihood produces a score for how well particular settings account for observed data.
log oddsnoun: Taking the natural logarithm of an event's probability divided by its opposite probability gives this statistical value.
log-prefix: This word-building form adds a meaning connected with words or speech.
log-likelihood ratio (LLR)noun: Subtracting two models' log likelihoods compares how strongly each accounts for the same observed data.
log-linear analysisnoun: A statistical method models logarithms of expected category counts to examine relationships among categorical variables.
log-normal distributionnoun: A probability distribution has this form when its positive values become normally distributed after taking logarithms.
logarithm (log)noun: The exponent needed to raise a chosen base to a particular positive number gives that number's logarithm.
logarithmic transformationnoun: Replacing positive data values with their logarithms can simplify multiplying relationships and reduce the influence of very large values.
logicnoun: Rules for deciding whether a conclusion follows correctly from given facts or statements.
logical inferencenoun: Reasoning follows valid rules to draw a conclusion from one or more starting statements.
logical necessitynoun: A conclusion must follow when specified starting statements are accepted and the rules of logic are applied correctly.
logical paradoxnoun: Seemingly sound reasoning produces a conclusion that appears impossible, contradictory, or absurd.
logical positivismnoun: A historical philosophy proposed that meaningful claims must either express logical truths or be testable through observation.
logical thinkingphrase: Using clear rules of logic so conclusions follow correctly from the information given.
logical-mathematical intelligencenoun: Gardner's multiple-intelligences theory proposes a distinct ability for reasoning, abstract patterns, calculations, and mathematical problem solving.
logicogrammatical disordernoun: A language difficulty associated with dominant parietal brain damage can place appropriate words in arrangements that change the intended meaning.
logistic functionnoun: A mathematical function produces an S-shaped curve often used to model growth that speeds up before approaching a limit.
logistic regression (LR)phrase: A statistical method that predicts the chance of one of two outcomes from one or more predictors.
logistic transformationnoun: The formula eˣ/(1 + eˣ) converts any real number into a value strictly between zero and one.
logitnoun: For probability p, the natural logarithm of p divided by one minus p expresses the corresponding log odds.
Logonoun: A child-focused computer language built to help kids practice problem solving and thinking skills.
logo- (log-)prefix: This combining form contributes the meaning of speech or words to a longer word.
logogennoun: A proposed memory unit recognizes a particular word, numeral, or letter when activated, making related knowledge available.
logographicadjective: A writing system has this quality when its symbols represent whole words or the smallest meaningful language units.
logopathynoun: This broad label covers disorders that affect a person's speech.
logopedicsnoun: This clinical discipline investigates difficulties with speaking and language, assesses communication needs, and provides treatment.
logorrheanoun: Speech becomes unusually abundant, rapid, difficult to control, and sometimes hard to follow, as can happen during mania.
logotherapynoun: Viktor Frankl's psychotherapy approach helps people discover personal meaning and purpose, including during difficult life experiences.
Lokian personalitynoun: An uncommon personality label describes a pattern of deception, manipulation, and wanting to upset other people.
Lolita complexnoun: A dated label describes an adult's strong or obsessive sexual interest in young girls.
London syndromenoun: A descriptive label identifies persistent, open refusal by hostages to comply with their captors' demands.
lonelinessnoun: Painful feelings that happen when someone lacks the closeness or social contact they want.
long axisnoun: An imaginary reference line extends lengthwise through a body or organ, running from head toward feet in the body.
long-delay conditioningnoun: A cue continues long before the event it predicts, allowing learned responses to weaken early and emerge closer to that event.
long-term carephrase: Ongoing health, mental health, or daily living support for people with lasting conditions or disabilities.
long-term care facilitynoun: A residential setting provides ongoing personal and medical support for people needing daily assistance without hospital-level care.
long-term depression (LTD)phrase: A lasting weakening of a synapse, the connection between neurons, after certain repeated stimulation patterns.
long-term memory (LTM)phrase: Stores knowledge and skills for long periods so they can be used much later.
long-term potentiation (LTP)phrase: A lasting strengthening of communication between neurons after repeated activation, thought to help form some memories.
long-term therapyphrase: Psychotherapy that continues for many months or years to work on deep, lasting problems.
long-wavelength pigmentnoun: A light-sensitive substance in one cone type responds best near 558 nanometers and helps the visual system distinguish colors.
longevitynoun: A person's actual lifespan, meaning how long that individual lives.
longilinealadjective: In historical body classifications, this describes a build that is relatively long and narrow.
longitudinaladjective: Describing a study that follows the same people or measurements over a long period of time.
longitudinal dataphrase: Measurements collected from the same people repeatedly over time to track change.
longitudinal designphrase: Studies the same people or variables repeatedly over time to track change.
longitudinal fissurenoun: A deep cleft separates the brain's two cerebral hemispheres, which remain connected by nerve pathways below.
longitudinal stabilitynoun: A psychological characteristic shows this consistency when a person's standing relative to others remains similar over time.
look anglenoun: The direction a person must look while operating equipment helps guide the design of comfortable, usable workstations.
look-saynoun: A reading instruction method teaches recognition and meaning of complete written words rather than emphasizing their individual sounds.
looking-glass selfnoun: A person's self-image develops partly through beliefs about how other people see and judge them.
loomingnoun: An approaching object's expanding image on the retina provides a visual signal that it is getting closer.
loose culturephrase: A diverse group where people value uniqueness, taking chances, and following social rules less strictly.
loosening of associationsnoun: A disruption in thought connections appears in speech that shifts between ideas with little clear relationship.
loperamidenoun: An opioid medicine treats diarrhea by slowing intestinal movement and usually has limited brain effects at recommended doses.
lorazepamnoun: A strong benzodiazepine medicine used to reduce anxiety and help calm people before surgery.
Lord’s paradoxnoun: Statistical analyses of group change can give conflicting conclusions depending on whether they adjust for initial differences between groups.
lordosisnoun: In animal behavior, females of many rodent species arch their backs during sexual receptivity, creating a posture that permits mating.
Lorenzini ampullaenoun: Specialized sensory organs in sharks and related fish detect weak electrical fields around them.
LOSabbreviation: Short for length of stay, this measures how long someone remains in a hospital during one admission.
loser effectnoun: Previous losses in contests can make an animal less likely to win later competitions for resources.
loss aversionnoun: People usually feel losses more strongly than equal-sized gains, so avoiding loss often guides choices.
loss of affectnoun: A person's capacity to react emotionally becomes greatly reduced or absent, producing little visible emotional response.
loss of consciousness (LOC)phrase: A person temporarily cannot be aware of events or control actions because normal consciousness has stopped.
lost letter procedurenoun: Researchers estimate community attitudes by comparing how often people mail planted letters addressed to groups holding opposing views.
lot acceptance samplingnoun: Inspecting randomly selected items from a batch helps determine whether the entire batch meets quality requirements.
Lou Gehrig’s diseasenoun: Also called amyotrophic lateral sclerosis, this progressive disease damages nerve cells controlling muscles, causing increasing weakness and movement difficulties.
loudnessnoun: How strong a sound seems to a listener, shaped mostly by intensity and also pitch and duration.
loudness summationnoun: Sounds heard together can have a perceived loudness equal to their separate loudnesses added together, depending on their frequencies.
Louis-Bar syndromenoun: Also called ataxia telangiectasia, this inherited condition causes worsening coordination, visibly widened tiny blood vessels, and often immune problems.
lovenoun: A strong, caring emotional bond marked by affection, pleasure near someone, and concern for that person's well-being.
love neednoun: In Maslow's proposed hierarchy, the third level involves wanting affection, belonging, and acceptance from other people.
love objectnoun: A person becomes the focus of someone's love, devotion, and sometimes sexual attraction.
love scalenoun: A questionnaire estimates someone's loving feelings toward another person, with different versions measuring different aspects of love.
love withdrawalphrase: A discipline method where parents threaten to stop showing love if a child misbehaves.
lovemapnoun: John Money proposed that people hold an inner picture of their preferred partner, relationship, and sexual experiences.
low birth weight (LBW)phrase: A baby weighing under 5.5 pounds at birth, no matter how early or late the birth happens.
low blood pressurephrase: When blood pushes too weakly against artery walls, causing dizziness, fainting, or tiredness.
low normaladjective: An older classification describes intellectual test scores near the lower end of average, roughly IQ 80 to 90.
low thresholdnoun: In some models of perception, random background noise can cross this detection boundary even when no signal is present.
low visionnoun: Sight remains limited enough to affect daily tasks despite the best available correction with ordinary lenses, medicine, or surgery.
low-ball techniquephrase: Getting agreement first, then adding hidden costs, makes people more likely to keep saying yes.
low-functioning autism (LFA)noun: An outdated, disputed label grouped autistic people by lower IQ scores and greater difficulties with everyday activities.
low-pass filternoun: A device or process lets lower frequencies through while reducing frequencies above a chosen cutoff.
low-technology assistive devicenoun: A simple tool made with inexpensive, commonly available technology helps a person with a disability perform activities.
Lowe syndromenoun: An inherited condition linked to the X chromosome mainly affects boys, causing eye and kidney problems and often developmental delays.
lower hingenoun: A statistical dividing point marks roughly the lowest quarter of ordered observations and helps summarize their spread.
lower motor neuronnoun: A nerve cell in the brainstem or spinal cord sends signals directly to skeletal muscle fibers.
lower quartilenoun: A dividing value in ordered data separates the lowest quarter of observations from the remaining three quarters.
lower real limitnoun: The bottom boundary of a rounded measurement marks the smallest underlying value that would receive that recorded score.
lowessnoun: Locally weighted scatterplot smoothing builds a trend curve by fitting small sections of data, giving nearby observations more influence.
loxapinenoun: An antipsychotic medicine reduces symptoms such as hallucinations by acting on brain receptors, including those for dopamine and serotonin.
loyaltynoun: Steady faithfulness to a person, group, or cause, even when staying committed is hard.
LPADabbreviation: The Learning Potential Assessment Device explores how someone learns by providing feedback during testing and observing their response.
LPC Scaleabbreviation: A rating scale used to tell whether a leader focuses more on relationships or on getting tasks done.
LPNabbreviation: A licensed practical nurse has completed practical nursing training and holds legal authorization to provide nursing care.
lPOAabbreviation: The lateral preoptic area is a brain region involved in sleep regulation and reproductive responses to changing daylight length.
LRabbreviation: A likelihood ratio compares how well two hypotheses account for observed data by dividing one likelihood by the other.
LREabbreviation: The least restrictive environment educates students with disabilities alongside other students as much as possible while meeting their learning needs.
LRPabbreviation: The lateralized readiness potential measures electrical differences between motor areas on opposite brain sides as someone prepares a hand response.
LSDabbreviation: A powerful hallucinogen that can cause vivid sensory distortions, mood changes, and altered thinking.
LTDabbreviation: Long-term depression is a lasting reduction in how strongly a connection between nerve cells transmits signals after certain activity patterns.
LTHabbreviation: Luteotropic hormone, also called prolactin, supports milk production and contributes to reproduction, body regulation, and parental behavior.
LTMabbreviation: Long-term memory keeps knowledge, experiences, and skills available beyond a brief period, sometimes for many years.
LTPabbreviation: A lasting strengthening of synapses, the connections between nerve cells, after repeated activity.
lucid dreamnoun: During sleep, a person recognizes that their ongoing experience is a dream and may sometimes influence what happens.
lucid intervalnoun: A temporary period of clearer thinking occurs after confusion, delirium, or other serious disruption of mental organization.
luciditynoun: In this legal sense, a person has enough mental clarity to be responsible for actions despite some limits in understanding.
Lucifer effectnoun: Zimbardo proposed that corrupt social settings can lead people who usually act ethically to behave unethically.
ludenoun: This slang name denotes methaqualone, a drug that slows nervous system activity and produces sedation and sleepiness.
Ludiomilnoun: This brand name identifies maprotiline, a medicine in the tetracyclic antidepressant group used to treat depression.
luesnoun: An older medical name for syphilis describes an infection that can sometimes affect the nervous system.
lumbaradjective: Describing the lower back area, including the lower section of the spine.
lumbar nervenoun: One of five paired spinal nerves emerging in the lower back carries sensory and movement signals between body and spinal cord.
lumbar puncturenoun: A medical procedure collects cerebrospinal fluid through a needle placed between bones in the lower back to help diagnose illness.
lumbosacral plexusnoun: An interconnected network of nerves from the lower back and pelvis carries signals to the lower body, including the legs.
lumennoun: A unit of luminous flux measures visible light output while accounting for human sensitivity to different wavelengths.
Luminalnoun: This brand name identifies phenobarbital, a barbiturate medicine used to control seizures and historically to promote sleep.
luminancenoun: A physical measure describes light traveling from a surface in a particular direction, expressed as candelas per square meter.
luminositynoun: In visual perception, the experienced brightness of a light depends on its output, the eye's sensitivity, and surrounding conditions.
luminosity coefficientnoun: A relative measure indicates how sensitive human vision is to a particular light wavelength under specified viewing conditions.
luminosity curvenoun: A graph shows how sensitive human vision is to light at different wavelengths.
luminous fluxnoun: A measurement in lumens describes total light output, weighted by how sensitive human eyes are to different wavelengths.
luminous intensitynoun: A measurement in candelas describes light output within a particular direction, accounting for human visual sensitivity.
lunacynoun: An outdated, stigmatizing label described mental illness and sometimes linked it to changes in the moon.
lunatic asylumnoun: This historical label named an institution where residents experiencing serious mental health difficulties were housed and treated.
Lunestanoun: This brand of eszopiclone is a sleep medicine used to treat difficulty falling or staying asleep.
Lupronnoun: This brand of leuprolide alters hormone signaling and, with continued treatment, lowers production of sex hormones.
lupus erythematosus (LE)noun: An autoimmune illness causes inflammation that can affect skin, joints, organs, and sometimes brain functioning.
lurasidonenoun: An antipsychotic medicine used for schizophrenia changes signaling at certain dopamine and serotonin receptors.
lurenoun: A wrong answer mixed with real studied items to distract someone during a memory test.
Luria–Nebraska Neuropsychological Battery (LNNB)noun: A standardized collection of tasks assesses brain-related abilities, including movement, language, memory, and reasoning, from age fifteen onward.
lurking variablenoun: An unnoticed factor influences an outcome and can make another measured factor appear to cause it.
lust murdernoun: A killing involves sexual arousal from causing another person's death, described as an extreme expression of sexual sadism.
luteal phasenoun: After ovulation, the emptied ovarian follicle becomes a hormone-producing structure that releases progesterone to support the uterine lining.
luteinizing hormone (LH)noun: A hormone from the front pituitary triggers ovulation in ovaries and stimulates androgen production in testes.
luteotropic hormonenoun: Another name for prolactin identifies a pituitary hormone supporting milk production and influencing reproduction and parental behavior.
luteotropinnoun: An alternative name for prolactin describes a hormone involved in producing milk, reproductive functions, and parental behavior.
Luvoxnoun: This brand of fluvoxamine treats obsessive-compulsive symptoms by slowing the reabsorption of serotonin between nerve cells.
luxnoun: A unit measures light arriving at a surface, with one lux equaling one lumen distributed over one square meter.
LVNabbreviation: A licensed vocational nurse has completed approved practical nursing education and holds legal permission to provide nursing care.
LVPabbreviation: Short for lysine vasopressin, this hormone form found in pigs helps conserve body water and increase blood pressure.
lycanthropynoun: A rare delusion involves believing oneself to be a wolf or another animal, or to undergo that transformation.
lygophilianoun: An uncommon descriptive label names an unusually strong desire to spend time in dark or gloomy surroundings.
Lyme diseasenoun: A bacterial infection spread by certain ticks can affect multiple body systems, sometimes causing problems with mood, memory, or concentration.
lymphocytenoun: An immune cell helps the body recognize threats, coordinate defenses, produce antibodies, or remove infected cells.
lymphokinenoun: A signaling protein released by lymphocytes helps coordinate immune activity, including encouraging other immune cells to multiply.
lynchingnoun: A mob kills someone outside lawful proceedings, often claiming punishment and, historically in the United States, enforcing racial domination.
lysergic acid diethylamidenoun: A powerful hallucinogenic drug, commonly called LSD, can alter perception, emotion, and thought through effects on serotonin receptors.
lysinenoun: An essential amino acid helps build proteins and must come from food because humans cannot make enough themselves.
lysine vasopressin (LVP)noun: A vasopressin variant found in pigs signals kidneys to retain water and can narrow small blood vessels.
lysinuric protein intolerancenoun: An inherited disorder disrupts transport of certain amino acids, causing poor protein tolerance and potentially affecting growth and organs.
lysisnoun: Symptoms of an illness or disorder ease gradually over time instead of ending suddenly.
lysosomenoun: A small compartment inside a cell contains enzymes that break down swallowed materials and cellular waste.

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