c.1400 (adj.), from L.L. deviantem, prp. of deviare "turn aside," from L. phrase de via, from de "off" + via "way." The noun, in the sexual sense, is attested from 1952; also deviate (n.), recorded since 1912.
deviant de·vi·ant (dē'vē-ənt) adj. Differing from a norm or from the accepted standards of a society. n. One that differs from a norm, especially a person whose behavior and attitudes differ from accepted social standards.