Adjective unfaithful has 4 senses
- unfaithful - not true to duty or obligation or promises; "an unfaithful lover"
Antonyms:  faithful, firm, loyal, truehearted, fast, true
 - unfaithful - having sexual relations with someone other than your husband or wife, or your boyfriend or girlfriend; "her husband was unfaithful"
Antonyms:  faithful, true to
 - faithless, traitorous, unfaithful - deliberately and abominably disloyal or likely to betray trust or confidence; "the faithless Benedict Arnold"; "a lying traitorous insurrectionist"
Antonym:  loyal (indirect, via disloyal)
 - unfaithful - not trustworthy; "an unfaithful reproduction"
Antonym:  accurate (indirect, via inaccurate)
 
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