cyberbullying the harassment, belittling, or threatening of someone via the Internet, e-mail, texting, blogs, social Web pages, etc.
dacnomania see mania.
decompensation the process of psychologic deterioration as a result of severe or long-term stress.
defense mechanism any thought or belief system employed to protect the ego from a lowering of esteem.
deindividualization the loss of social inhibitions and acting out of aggressions and impulses due to anonymity in a crowd or anonymity behind a mask or costume.
deja vu the haunting feeling that one has experienced something or seen something before, even though there is no conscious memory of it.
delirium tremens alcohol poisoning characterized by hallucinations, trembling, and paranoia.
delusion a false belief about oneself or the world held despite evidence to the contrary.
delusional disorder a disorder characterized by frequent, irrational thoughts about being followed, poisoned, infected with a disease, lied to, or, sometimes, being the subject of someone else's infatuation. The disorder, however, does not include outlandish delusions on the level of aliens removing part of one's brain or leprechauns living under one's bed.
dementia loss of intellectual faculties with accompanying emotional disturbances due to organic brain disorder.
demonomania see mania.
denial an ego defense through which any harsh reality, such as the possibility of dying prematurely or that one is grossly overweight, is disbelieved or vigorously rejected.
dependent personality disorder a disorder characterized by passivity, helplessness, indecisiveness, and an overdependency on other people.
depersonalization a dissociative reaction characterized by feelings of unreality, separation, isolation, and a loss of identity.
depression feelings of sadness, ranging from a temporary case of the blues, which is easily cured through pleasurable activities, to clinical depression, which requires medical intervention.
derailment going off one's conversational track into unrelated subjects.
derealization an uncomfortable perception or feeling of unreality or strangeness.
desensitization the cure of a fear or phobia by gradual, step-by-step exposure to the source of the fear.
detachment social aloofness, due to apathy, denial, intellectualization, etc.
Diagnostic Statistical Manual a comprehensive classification system with criteria for diagnosis, used by mental health professionals. Commonly known as the DSM.
diffusion of responsibility the tendency for people in groups to fail to take action in an emergency due to the belief that "someone else" will act.
disinhibition the complete loss of normal human inhibition, allowing the freedom to act on animal or primitive impulses, sometimes caused by drug use or brain injury.
displacement a defense mechanism involving the transfer of feelings or actions from an unacceptable to an acceptable form.
dissociation a collective term for the various symptoms that occur when anxiety is handled by a splitting off of part of the personality and the breaking up of the sense of self, with symptoms ranging from a sense of unreality and loss of identity to fainting.
dissonance inconsistency between one's actions and one's attitudes.
distractability one's level of attention and ability to focus. May sometimes refer to a short attention span.
dominance in a social hierarchy, one's leadership and command over others, a behavior or standing that varies widely according to age, status, physical prowess, gender, intelligence, verbal skills, aggressiveness, testosterone levels, and the ability to network and form alliances with others.
doraphobia see phobia.
double blind an experiment in which neither the investigator nor the subjects know which group is receiving a real treatment and which a placebo.
dysfunction poor or maladjusted functioning; unhealthy behavior.
dyslexia a learning disorder in which a reader perceives letters and words backward or in the wrong order or may not see some letters or words at all.
dyspareunia genital pain experienced during intercourse, unrelated to any identifiable physical cause, seen in victims of rape and molestation.
echolalia a disorder in which the person repeats the last words heard.
echopraxia the involuntary mimicking of another's body movements and gestures.
ecopsychology the science of calming one's mind or relieving anxiety and depression through such natural outdoor activities as backpacking, gardening, or creating compost heaps.
ego in psychoanalytic theory, the personality component that involves rationality and governs the self.
egocentrism the inability to see someone else's point of view.
Electra complex an unconscious sexual desire of a daughter for her father.
electroconvulsive therapy electric shock therapy administered to the brain.
electroencephalograph (EEG) a device that measures the electrical activity of the brain.
emotional contagion the spreading of similar feelings throughout a group, as when one family member in a foul mood can cause others to act badly as a response, a phenomenon at the forefront of mob behavior.
emotional intelligence the ability to regulate and master one's emotions in order to think more clearly, to make better decisions, and to avoid trouble with others.
empty-nest syndrome the feelings of loss, depression, and anxiety experienced by a parent whose grown children have all moved out of the house.
enuresis bedwetting.
EQ short for emotional quotient, the emotional equivalent of IQ.
ethnocentricity believing your own beliefs and values are the only right ones; cultural bias.
ethnocentrism the belief that one's own culture and way of life are superior to all others.
etiology the causes of a disorder.
euphoria a feeling of great happiness.
evolutionary psychology the study of behavior as it has evolved through natural selection, as in the universal fear of snakes or inhibition around strangers or the tendency to choose physically robust or attractive mates, with many traits and personality quirks thriving because of their long-term survival value.
exhibitionism the compulsive desire to reveal one's genitals.
existentialism the philosophical belief that people have the freedom to make choices, decide the meaning of reality, and take responsibility for their existence.
expansive mood a mental state characterized by the free expression of one's thoughts and moods, without inhibition.
explosive personality a person prone to explosive outbursts.
extinction the fading and ultimate extinguishing of a behavior or thought process that maintained a phobia or other emotional dysfunction.
extroversion a personality trait characterized by an outward focus rather than an introspective one, marked by outgoing social behavior or great enjoyment in the company of others.