1640s, "animating spirit," from Latin psyche, from Greek psykhē "the soul, mind, spirit; life, one's life, the invisible animating principle or entity which occupies and directs the physical body; understanding, the mind (as the seat of thought), faculty of reason" (personified as Psykhē, the beloved of Eros), also "ghost, spirit of a dead person;" probably akin to psykhein "to blow, cool," from PIE root *bhes- "to blow, to breathe" (source also of Sanskrit bhas-), "Probably imitative" [Watkins].

Also in ancient Greek, "departed soul, spirit, ghost," and often represented symbolically as a butterfly or moth. The word had extensive sense development in Platonic philosophy and Jewish-influenced theological writing of St. Paul (compare spirit (n.)). Meaning "human soul" is from 1650s. In English, psychological sense "mind," is attested by 1910.

In the Jewish-Alexandrine Pauline, and Neo-Platonist psychology, the psyche is in general treated as the animating principle in close relation to the body, whereas the pneuma (as representing the divine breath breathed into man), the nous, and the Logos (q.v.) stand for higher entities. They are the more universal, the more divine, the ethically purer. By this more explicit separation of the intellectual and ethical activities from the physiological the conception of the mental or psychical (in the modern sense) was at length reached. ["Dictionary of Philosophy and Psychology," J.M. Baldwin, ed., London, 1902]

occasionally psychodelic, 1956, of drugs, suggested by British-born Canadian psychiatrist Humphry Osmond in a letter to Aldous Huxley and used by Osmond in a scientific paper published the next year; from Greek psykhē "mind" (see psyche) + dēloun "make visible, reveal," from dēlos "visible, clear," from PIE root *dyeu- "to shine." In popular use from 1965 with reference to anything producing effects similar to that of a psychedelic drug or enhancing the effects of such a drug. As a noun from 1956.

1875, from psychiatry + -ist.

A psychiatrist is a man who goes to the Folies Bergère and looks at the audience. [Anglican Bishop Mervyn Stockwood, 1961]

An older name was mad-doctor (1703); also psychiater "expert in mental diseases" (1852), from Greek psyche + iatros. Also see alienist.

1846, from French psychiatrie, from Medieval Latin psychiatria, literally "a healing of the soul," from Latinized form of Greek psykhē "mind" (see psyche) + iatreia "healing, care" (see -iatric).

1872, "of or pertaining to the human soul" (earlier psychical, 1640s), from Greek psykhikos "of the soul, spirit, or mind" (opposed to somatikos), also (New Testament) "concerned with the life only, animal, natural," from psykhē "soul, mind, life" (see psyche). Meaning "characterized by psychic gifts" first recorded 1871.