1. Not faithful; not observant of promises, vows, allegiance, or duty; violating trust or confidence; treacherous; perfidious; as, an unfaithful subject; an unfaithful agent or servant.
My feet, through wine, unfaithful to their weight. --Pope.
His honor rooted in dishonor stood,
And faith unfaithful kept him falsely true. --Tennyson.
2. Not possessing faith; infidel. [R.]
-- Un*faith*ful*ly, adv. -- Un*faith*ful*ness, n.
adj 1: not true to duty or obligation or promises; "an unfaithful
lover" [ant: faithful]
2: having sexual relations with someone other than your husband
or wife, or your boyfriend or girlfriend; "her husband was
unfaithful" [ant: faithful]
3: deliberately and abominably disloyal or likely to betray
trust or confidence; "the faithless Benedict Arnold"; "a
lying traitorous insurrectionist" [syn: faithless, traitorous]
4: not trustworthy; "an unfaithful reproduction"