a. 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. [ 1913 Webster ]
My feet, through wine, unfaithful to their weight. Pope. [ 1913 Webster ]
His honor rooted in dishonor stood, And faith unfaithful kept him falsely true. Tennyson. [ 1913 Webster ]
2. Not possessing faith; infidel. [ R. ] Milton. [ 1913 Webster ]
-- Un*faith"ful*ly, adv. -- Un*faith"ful*ness, n. [ 1913 Webster ]