unfaithful
1. [ adjective ] not true to duty or obligation or promises
Examples:

"an unfaithful lover"

Related terms: faithful apostate punic untrue adulterous untrustworthy inconstant fidelity
2. [ adjective ] (sexuality) having sexual relations with someone other than your husband or wife, or your boyfriend or girlfriend
Examples:

"her husband was unfaithful"

Related terms: faithful adulterous adulterous
3. [ adjective ] deliberately and abominably disloyal or likely to betray trust or confidence
Synonyms: traitorous faithless
Examples:

"the faithless Benedict Arnold" "a lying traitorous insurrectionist"

Related terms: disloyal
4. [ adjective ] not trustworthy
Examples:

"an unfaithful reproduction"

Related terms: inaccurate
Similar spelling:   unfaithfully