unfaithful
adjective
1. not true to duty or obligation or promises
- an unfaithful lover
Similar word(s): inconstant, apostate, perfidious, punic, treacherous, untrue, untrustworthy, untrusty
2. having sexual relations with someone other than your husband or wife, or your boyfriend or girlfriend
- her husband was unfaithful
Similar word(s): adulterous, cheating
3. having the character of, or characteristic of, a traitor
Similar word(s): disloyal, faithless, traitorous, treasonable, treasonous
4. not trustworthy
- an unfaithful reproduction
Similar word(s): inaccurate