- unfaithful (adj.)
[unfaithful 词源字典]
- mid-14c., "acting falsely," from un- (1) "not" + faithful. In Middle English it also had a sense of "infidel, unbelieving, irreligious" (late 14c.). Sense of "not faithful in marriage" is attested from 1828. Related: Unfaithfully; unfaithfulness.[unfaithful etymology, unfaithful origin, 英语词源]