adjective
- not adhering to allegiance, promises, vows, or duty: the faithless behavior of Benedict Arnold.
- not trustworthy; unreliable.
- without trust or belief.
- being without religious faith.
- (among Christians) bereft of Christian faith.
adjective
- unreliable or treacherous
- dishonest or disloyal
- having no faith or trust
- lacking faith, esp religious faith
c.1300, “unbelieving,” from faith + -less. Meaning “insincere” is mid-14c. Related: Faithlessly; faithlessness.