1847, "pertaining to the relation between mind and body," from Greek psykhē "mind" (see psyche) + sōmatikos, from sōma (genitive sōmatos) "body" (see somato-). Applied from 1938 to physical disorders with psychological causes. Etymologically it could as easily apply to emotional disorders with physical causes, but it is rarely used as such.

1889, coined from psychosis, on the model of neurotic/neurosis, from Greek psykhē "understanding, the mind (as the seat of thought), faculty of reason" (see psyche).