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]