Online Etymology Dictionary

psychology (n.): 1650s, "study of the soul," from Modern Latin psychologia, probably coined mid-16c. in Germany by Melanchthon from Latinized form of Greek psykhe- "breath, spirit, soul" (see psyche) + logia "study of" (see -logy). Meaning "study of the mind" first recorded 1748, from Christian Wolff's "Psychologia empirica" (1732); main modern behavioral sense is from early 1890s.
psychologist (n.): 1727; see psychology + -ist.
parapsychology (n.): 1924, from para- (1) "beside" + psychology.
psychobabble (n.): 1976, from psycho- (representing psychology) + babble (n.). Earlier was psychologese (1961).
psych: as a noun, short for psychology in various senses (e.g. as an academic study, in student slang by 1895). As a verb, first attested 1917 as "to subject to psychoanalysis," short for psychoanalyze. From 1934 as "to outsmart" (also psych out); from 1963 as "to unnerve." However to psych (oneself) up is from 1972; to be psyched up is attested from 1968.
psychological (adj.): 1680s; see psychology + -ical. Related: Psychologically. Psychological warfare recorded from 1940. Psychological moment was in vogue from 1871, from French moment psychologique "moment of immediate expectation of something about to happen."
The original German phrase, misinterpreted by the French & imported together with its false sense into English, meant the psychic factor, the mental effect, the influence exerted by a state of mind, & not a point of time at all, das Moment in German corresponding to our momentum, not our moment. [Fowler]
behavioral (adj.): 1927, in psychology, from behavior + -al (1).
self-image (n.): also self-image, 1904 in psychology, from self- + image (n.).
somatization (n.): 1909 in biology (Rignano); 1920 in psychology; from somato- "body" + -ization.
empathize (v.): 1894, from empathy + -ize. By 1919 in psychology. Related: Empathized; empathizing.
introject (v.): 1902 in psychology, probably a back-formation from introjection. Related: Introjected; introjecting.
perseverate (v.): 1915, in psychology, a back-formation from perseveration. Related: Perseverating; perseverative.
ambivalent (adj.): 1916, originally a term in psychology; back-formation from ambivalence. In general use by 1929.
hedonistic (adj.): 1849, from hedonist + -ic. The earlier adjectival form was hedonic. By 1901 in psychology, "of the nature of pleasure-seeking."
depressive (adj.): 1610s, from Latin depress-, past participle stem of deprimere (see depress) + -ive. In psychology, from 1905.
thanatos (n.): "death instinct," 1935, in Freudian psychology, from Greek thanatos "death" (see thanato-).
construct (n.): 1871 in linguistics, 1890 in psychology, 1933 in the general sense of "anything constructed;" from construct (v.).
ambisexual (adj.): "unisex" (of clothing), also "bisexual," 1912 in the jargon of psychology, from ambi- + sexual. As a humorous coinage based on ambidextrous, ambisextrous is recorded from 1929.
surgent (adj.): "rising in waves," 1590s, from Latin surgentem (nominative surgens) "rising," present participle of surgere "to rise" (see surge (n.)). In psychology from 1933.
acting (n.): c. 1600, "performance of deeds;" 1660s, "performance of plays;" verbal noun from present participle of act (v.). Acting out in psychology is from 1945.
libidinal (adj.): in psychology jargon, 1922, in Joan Riviere's translation of Freud, from comb. form of libido (Latin genitive libidinis) + -al (1).
parapraxis (n.): "faulty action, blunder," 1904, from Modern Latin, from para- "contrary" (see para- (1)) + Greek praxis "a doing, transaction, business" (see praxis). In psychology, a minor error held to reveal a subconscious motive.
interpersonal (adj.): 1911 (OED finds an isolated use from 1842), from inter- "between" + person (n.) + -al. Introduced in psychology (1938) by H.S. Sullivan (1892-1949) to describe behavior between people in an encounter. Related: Interpersonally.
ambivert (n.): "person exhibiting features of an extrovert and an introvert," coined by Kimball Young in "Source Book for Social Psychology" (1927), from ambi- "about, around" + Latin vertere, as in introvert. Related: Ambiversion.
proactive (adj.): also pro-active, of persons or policies, as an opposition to reactive, 1921, from pro- + active. From 1933, in psychology (learning theory). Related: Proactively; proactiveness; proactivity.
inversion (n.): 1550s, "act of inverting;" 1590s, "state of being inverted," from Latin inversionem (nominative inversio) "an inversion," noun of action from past participle stem of invertere "turn about, turn upside-down" (see invert). Meteorological sense is from 1902. In old psychology, "homosexuality" (1895, short for sexual inversion) but in later psychology "identification with the opposite sex" (1958).
unconscious (adj.): 1712, "unaware, not marked by conscious thought," from un- (1) "not" + conscious. Meaning "temporarily insensible, knocked out" is recorded from 1860. Related: Unconsciously; unconsciousness. In psychology, the noun the unconscious (1876) is a loan-translation of German das Unbewusste. The adjective in this sense is recorded from 1912.
anthropology (n.): "science of the natural history of man," 1590s, originally especially of the relation between physiology and psychology, from Modern Latin anthropologia or coined independently in English from anthropo- + -logy. In Aristotle, anthropologos is used literally, as "speaking of man."
extraverted (adj.): in modern psychology, 1915, a variant of extroverted (see extrovert). Related: Extravert (n.), for which also see extrovert. There was a verb extravert in mid- to late 17c. meaning "to turn outward so as to be visible," from Latin extra "outward" + vertere "to turn."
extroversion (n.): mid-17c., "condition of being turned inside out," noun of action from obsolete verb extrovert (v.) "to turn inside out," from extro- + Latin vertere (see versus). Earliest as a word in mysticism; modern use in psychology attested by 1920.
semiotic (adj.): 1620s, "of symptoms, relating to signs of diseases," from Greek semeiotikos "significant," also "observant of signs," adjective form of semeiosis "indication," from semeioun "to signal, to interpret a sign," from semeion "a sign, mark, token," from sema "sign" (see semantic). Its use in psychology dates to 1923. Related: Semiotical (1580s).
pansexual (adj.): 1926 (pansexualism is from 1917), from pan- + sexual. Originally in reference to the view that the sex instinct plays the primary part in all human activity, mental and physical; this was held by his critics to be the view of Freud, therefore a term of reproach leveled at early psychology.
archetype (n.): "original pattern from which copies are made," 1540s [Barnhart] or c. 1600 [OED], from Latin archetypum, from Greek arkhetypon "pattern, model, figure on a seal," neuter of adjective arkhetypos "first-moulded," from arkhe- "first" (see archon) + typos "model, type, blow, mark of a blow" (see type). Jungian psychology sense of "pervasive idea or image from the collective unconscious" is from 1919. Jung defined archetypal images as "forms or images of a collective nature which occur practically all over the earth as constituents of myths and at the same time as autochthonous individual products of unconscious origin." ["Psychology and Religion" 1937]
homosexual (adj.): 1892, in C.G. Chaddock's translation of Krafft-Ebing's "Psychopathia Sexualis," from German homosexual, homosexuale (by 1880, in Gustav Jäger), from homo-, comb. form of Greek homos "same" (see homo- (1)) + Latin-based sexual.
'Homosexual' is a barbarously hybrid word, and I claim no responsibility for it. It is, however, convenient, and now widely used. 'Homogenic' has been suggested as a substitute. [H. Havelock Ellis, "Studies in Psychology," 1897]
Sexual inversion (1883, later simply inversion, by 1895) was an earlier clinical term for "homosexuality" in English, said by Ellis to have originated in Italian psychology writing. See also uranian. Unnatural love was used 18c.-19c. for homosexuality as well as pederasty and incest. Related: Homosexually.
ideal (adj.): early 15c., "pertaining to an archetype or model," from Late Latin idealis "existing in idea," from Latin idea in the Platonic sense (see idea). Senses "conceived as perfect; existing only in idea," are from 1610s. Ideagenous "generating ideas" (1839) is a word from early psychology, apparently coined by Dr. Thomas Laycock, house surgeon to York County Hospital ["Edinburgh Medical and Surgical Journal," vol. 52].
Gestalt (n.): 1922, from German Gestaltqualität (1890, introduced by German philosopher Christian von Ehrenfels, 1859-1932), from German gestalt "shape, form, figure, configuration, appearance," abstracted from ungestalt "deformity," noun use of adj. ungestalt "misshapen," from gestalt, obsolete past participle of stellen "to set, place, arrange" (see stall (n.1)). As a school of psychology, it was founded c. 1912 by M. Wertheimer, K. Koffka, W. Köhler.
affect (n.): late 14c., "mental state," from Latin noun use of affectus "furnished, supplied, endowed," figuratively "disposed, constituted, inclined," past participle of afficere "to do; treat, use, manage, handle; act on; have influence on, do something to," a verb of broad meaning, from ad- "to" (see ad-) + facere (past participle factus) "to make, do" (see factitious). Perhaps obsolete except in psychology. Related: Affects.
encounter (n.): c. 1300, "meeting of adversaries, confrontation," from Old French encontre "meeting; fight; opportunity" (12c.), noun use of preposition/adverb encontre "against, counter to" from Late Latin incontra "in front of," from Latin in- "in" (see in- (2)) + contra "against" (see contra). Modern use of the word in psychology is from 1967, from the work of U.S. psychologist Carl Rogers (1902-1987). Encounter group attested from 1967.
persona (n.): 1917, "outward or social personality," a Jungian psychology term, from Latin persona "person" (see person). Used earlier (1909) by Ezra Pound in the sense "literary character representing voice of the author." Persona grata is Late Latin, literally "an acceptable person," originally applied to diplomatic representatives acceptable to the governments to which they were sent; hence also persona non grata (plural personæ non gratæ).
fusion (n.): 1550s, "act of melting by heat," from Middle French fusion or directly from Latin fusionem (nominative fusio) "an outpouring, effusion," noun of action from fusus, past participle of fundere "to pour, melt" (see found (v.2)). Meaning "union or blending of different things; state of being united or blended" is by 1776; used especially in 19c, of politics, in early 20c. of psychology, atoms, and jazz (in nuclear physics sense, first recorded 1947; in musical sense, by 1972).
role (n.): "part or character one takes," c. 1600, from French rôle "part played by a person in life," literally "roll (of paper) on which an actor's part is written," from Old French rolle (see roll (n.)). Meaning "function performed characteristically by someone" is from 1875. In the social psychology sense from 1913. Role model first attested 1957.
plateau (n.): 1796, "elevated tract of relatively level land," from French plateau "table-land," from Old French platel (12c.) "flat piece of metal, wood, etc.," diminutive of plat "flat surface or thing," noun use of adjective plat "flat, stretched out" (12c.), perhaps from Vulgar Latin *plattus, from Greek platys "flat, wide, broad" (see plaice). Meaning "stage at which no progress is apparent" is attested from 1897, originally in psychology of learning. In reference to sexual stimulation from 1960.
subliminal (adj.): 1873, "below the threshold" (of consciousness or sensation), formed from Latin stem of sublime (Latin limen, genitive liminis) + -al (1)). Apparently a loan-translation of German unter der Schwelle (des Bewusstseins) "beneath the threshold (of consciousness)," from Johann Friedrich Herbart (1776-1841), author of a textbook on psychology published in 1824. The scare over subliminal advertising came in 1957. Related: Subliminally.
semantic (adj.): 1894, from French sémantique, applied by Michel Bréal (1883) to the psychology of language, from Greek semantikos "significant," from semainein "to show by sign, signify, point out, indicate by a sign," from sema "sign, mark, token; omen, portent; constellation; grave" (Doric sama), from PIE root *dheie- "to see, look" (source also of Sanskrit dhyati "he meditates;" see zen).
aversion (n.): "a turning away from," 1590s; figurative sense of "mental attitude of repugnance" is from 1650s, from Middle French aversion and directly from Latin aversionem (nominative aversio), noun of action from past participle stem of aversus "turned away, backwards, behind, hostile," itself past participle of avertere (see avert). Earlier in the literal sense of "a turning away from" (1590s). Aversion therapy in psychology is from 1950.
significant (adj.): 1570s, "having a meaning," from Latin significantem (nominative significans, present participle of significare "make known, indicate" (see signify). Earlier in the same sense was significative (c. 1400). Often "having a special or secret meaning," hence "important" (1761). Related: Significantly. Significant figure is from 1680s. Significant other (n.) attested by 1961, in psychology, "the most influential other person in the patient's world."
innervate (v.): "stimulate through the nerves," 1870, a back-formation from innervation "sending of a stimulus through the nerves" (1828), which is perhaps modeled on French innervation; see in- (2) "in" + nerve (n.) + -ate. Related: Innervated. Earlier in English the same word (but from the other in-) meant "to lose feeling or sensation" (1848), and, as an adjective, "without feeling" (1737). Innervation in psychology is from 1880, translated from German Innervationsgefühl.
libidinous (adj.): "lustful," mid-15c., from Old French libidineus "sinful, lusty" (13c., Modern French libidineux) or directly from Latin libidinosus "full of desire, lustful," from libido "pleasure, desire, sensual passion, lust" (see libido). Related: Libidinously; libidinousness; libidinosity. These are older in English than libido, libidinal, which are from modern psychology.
defense (n.): c. 1300, "forbidding, prohibition," also "action of guarding or protecting," from Old French defense, from Latin defensus, past participle of defendere "ward off, protect" (see defend). But it also arrived (without the final -e) from Old French defens, from Latin defensum "thing protected or forbidden," neuter past participle of defendere.

Defens was assimilated into defense, but not before it inspired the alternative spelling defence, via the same tendency that produced hence (hennis), pence (penies), dunce (Duns). First used 1935 as a euphemism for "national military resources." Defense mechanism in psychology is from 1913.
herd (n.1): Old English heord "herd, flock, company of domestic animals," also, rarely, "a keeping, care, custody," from Proto-Germanic *herdo (source also of Old Norse hjorð, Old High German herta, German Herde, Gothic hairda "herd"), from PIE *kerdh- "a row, group, herd" (source also of Sanskrit śárdhah "herd, troop," Old Church Slavonic čreda "herd," Greek korthys "heap," Lithuanian kerdžius "shepherd"). Of any animals, wild or domestic, from c. 1200; of people, often in a disparaging sense, from c. 1400. Herd instinct in psychology is first recorded 1886.