Psychology Vocabulary: Key Terms and Definitions

Words from psychology show up everywhere: in classrooms, therapy offices, news articles, workplace training, and ordinary conversations between friends. A person might talk about being "triggered," accuse someone of "projecting," or describe a decision as shaped by "confirmation bias." Those words can be useful, but they also carry technical meanings that are easy to blur. This guide explains common psychology vocabulary across major areas of the field so you can use the terms with more care and understand them when you meet them in reading, study, or discussion.

How Psychology Talks About the Mind

The term "psychology" is built from Greek psykhē, meaning soul, mind, or breath, and logos, meaning study or word. As a formal science, psychology is fairly recent. It broke away from philosophy in the late nineteenth century, especially after Wilhelm Wundt opened the first psychology laboratory in Leipzig, Germany, in 1879.

The field's terminology comes from several sources: Greek and Latin roots, German-language experimental psychology, and English terms created or popularized by major figures such as Sigmund Freud, Carl Jung, B.F. Skinner, and others. Some words sound familiar because they are used in everyday speech, yet their professional meanings are often narrower or more exact. That is why vocabulary matters so much in psychology.

Core Ideas to Know First

• Hypothesis — From Greek hupothesis; a prediction about behavior or mental activity that can be tested.
• Behavior — The actions an organism performs. Psychology examines both overt behavior that can be seen and covert mental processes that occur internally.
• Stimulus — From Latin, meaning a goad or prod; any object, event, or condition that brings about a response.
• Response — A reaction produced by a stimulus.
• Cognition — From Latin cognitio, "getting to know"; mental activity such as thinking, learning, remembering, knowing, and solving problems.
• Perception — From Latin perceptio, "receiving" or "collecting"; the brain's process of making sense of sensory input.
• Consciousness — Awareness of one's thoughts, emotions, bodily states, and environment.
• Nature vs. Nurture — The long-running question of whether genes or environment have the stronger influence on behavior.

Words from Cognitive Psychology

• Attention — The mental process of selecting certain information for focus while filtering out other input.
• Memory — The ability to encode, keep, and later retrieve information.
• Working memory — The system used to hold information in mind and work with it during demanding tasks.
• Short-term memory — Brief storage that lasts roughly 20–30 seconds unless the information is rehearsed.
• Long-term memory — Storage of information over extended periods, often relatively permanent.
• Schema — From Greek skhēma, meaning form or figure; a mental structure used to organize and interpret information.
• Heuristic — From Greek heuriskein, "to find"; a quick mental rule of thumb used in decision-making.
• Bias — A consistent tendency in thinking that moves judgment away from strict rationality.
• Confirmation bias — The habit of looking for, noticing, or favoring information that supports what one already believes.
• Cognitive dissonance — The discomfort caused by holding conflicting beliefs, attitudes, or values at the same time; the term was coined by Leon Festinger in 1957.
• Metacognition — Awareness of one's own thinking; often described as thinking about thinking.

Terms for Human Development

• Development — The pattern of growth and change that starts at conception and continues across the lifespan.
• Maturation — From Latin maturare, "to ripen"; biological growth that makes orderly changes in behavior possible.
• Temperament — From Latin temperamentum, "mixture"; inborn personality tendencies visible from infancy.
• Attachment — The emotional connection between an infant and caregiver, studied in depth by John Bowlby and Mary Ainsworth.
• Socialization — The process of learning the rules, expectations, values, and habits of one's culture.
• Critical period — A developmental window in which certain experiences are necessary for normal development.
• Puberty — From Latin pubertas, "age of maturity"; the biological shift into sexual maturity.
• Identity — From Latin identitas, "sameness"; a person's sense of self, especially prominent in Erik Erikson's work on adolescence.

Vocabulary of Social Psychology

• Social influence — The way other people shape an individual's thoughts, emotions, and actions.
• Conformity — Changing behavior so it fits group norms; associated with Solomon Asch's research.
• Obedience — Following the directions of an authority figure, famously studied by Stanley Milgram.
• Groupthink — A group decision-making problem in which the wish for agreement pushes aside realistic evaluation of options.
• Attribution — The process of explaining why behavior occurs, often by pointing to internal traits or external situations.
• Stereotype — From Greek stereos, "solid," and typos, "impression"; a broad belief applied to members of a group.
• Prejudice — From Latin praejudicium, "pre-judgment"; a preformed attitude toward a group, usually a negative one.
• Bystander effect — The tendency for people to be less likely to help when others are present.
• Prosocial behavior — Actions meant to help or benefit other people.
• Empathy — From Greek empatheia, "passion" or "affection"; the capacity to understand and share another person's feelings.

Mental Health and Clinical Terms

• Depression — From Latin depressio, "pressing down"; a mood disorder marked by lasting sadness and loss of interest.
• Anxiety — From Latin anxietas, "distress"; ongoing excessive worry that disrupts normal functioning.
• Phobia — From Greek phobos, "fear"; a strong, irrational fear focused on a particular object or situation.
• Trauma — From Greek trauma, "wound"; a deeply distressing event or the psychological reaction that follows it.
• PTSD (Post-Traumatic Stress Disorder) — A disorder that can develop after experiencing or witnessing a terrifying event.
• Psychosis — A serious mental state involving a break from reality.
• Neurosis — From Greek neuron, "nerve"; an older label for milder mental disorders, now mostly replaced by more specific diagnoses.
• Therapy / Psychotherapy — From Greek therapeia, "healing"; treatment of mental health conditions using psychological techniques.
• CBT (Cognitive Behavioral Therapy) — A form of therapy aimed at changing unhelpful patterns of thought and behavior.
• Resilience — The ability to recover after adversity and adjust to difficult circumstances.

Behavior and Learning Terms

• Conditioning — Learning that happens through association, as in classical conditioning, or through consequences, as in operant conditioning.
• Classical conditioning — Learning to connect a neutral stimulus with a meaningful stimulus; Pavlov's dogs are the classic example.
• Operant conditioning — Learning shaped by rewards and punishments, closely associated with B.F. Skinner.
• Reinforcement — A consequence that makes a behavior more likely to occur again.
• Punishment — A consequence that makes a behavior less likely to happen again.
• Habituation — A weaker response to a stimulus after repeated exposure to it.
• Extinction — The gradual fading of a conditioned response.

Freud, Jung, and Psychoanalysis

Many words associated with Sigmund Freud moved out of psychoanalytic theory and into general English:

• Unconscious — Mental activity that takes place outside conscious awareness.
• Id — From Latin, meaning "it"; the instinctive, primitive part of personality.
• Ego — From Latin, meaning "I"; the rational part of personality that deals with reality.
• Superego — The moral part of personality, built from internalized social rules.
• Denial — Refusing to accept reality as it is.
• Repression — Keeping painful or upsetting thoughts out of conscious awareness.
• Projection — Assigning one's own unacceptable feelings or impulses to someone else.
• Sublimation — Redirecting unacceptable impulses into activities society accepts.
• Freudian slip — A mistake in speech thought to expose an unconscious idea.

Carl Jung contributed several widely recognized terms as well, including archetype, meaning a universal inherited pattern of thought; introvert/extrovert, describing inward-focused and outward-focused personality types; and the collective unconscious, referring to shared inherited memories.

How Psychologists Study Behavior

• Variable — Any factor in a study or experiment that can change.
• Experiment — A controlled study designed to test how one variable affects another.
• Sample — The portion of a larger population that researchers actually study.
• Correlation — A statistical connection between two variables; correlation does not prove causation.
• Placebo — From Latin, "I shall please"; an inactive treatment given to a control group.
• Double-blind study — A study in which neither the participants nor the researchers know who receives the treatment and who receives the placebo.
• Reliability — The degree to which a measurement tool gives consistent results.
• Validity — The extent to which a test measures what it says it measures.

Psychology Terms People Use Casually

Some psychology words have become everyday labels. Casual use is not always the same as clinical use, so context matters:

• "Gaslighting" — From the 1944 film Gaslight; manipulating a person so they begin to doubt their own sense of reality.
• "OCD" — Obsessive-Compulsive Disorder is a clinical condition, though people often use the term casually for neatness or a preference for order.
• "Narcissist" — In clinical use, Narcissistic Personality Disorder is a serious diagnosis; in casual speech, the word often means someone extremely self-centered.
• "Triggered" — Clinically, it refers to stimuli that set off PTSD responses; informally, it is used in a much broader way.
• "Boundaries" — Limits a person sets to protect emotional and mental well-being.
• "Trauma bonding" — An attachment that develops through repeated cycles of abuse and positive reinforcement.

Final Thoughts

Psychology vocabulary gives us sharper language for discussing thought, emotion, learning, development, relationships, and mental health. Terms such as id, ego, cognitive dissonance, resilience, and growth mindset have influenced both professional study and everyday self-understanding. Learning these words can support academic work, improve conversations about mental health, and make it easier to describe human behavior with accuracy and empathy. For more background on where many of these terms come from, see our guides to Greek words in English and Latin words in English.