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.[unconscious etymology, unconscious origin, 英语词源]