| Unfaithful 1. (a.) 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. 2. (a.) Not possessing faith; infidel. Thesaurus Entries derelict, disaffected, disloyal, disregardful, faithless, FALSE, fickle, inattentive, inconstant, inobservant, negligent, nonadherent, noncompliant, nonconforming, nonobservant, not true to, of bad faith, perfidious, recreant, traitorous, treacherous, trothless, uncompliant, unconforming, unloyal, unobservant, unsteadfast, untrue |