unfaithful
1 deceitful, disloyal, faithless, false, false-hearted, perfidious, recreant (archaic) traitorous, treacherous, treasonable, unreliable, untrustworthy
2 adulterous, faithless, fickle, inconstant, two-timing (informal) unchaste, untrue
3 distorted, erroneous, imperfect, imprecise, inaccurate, inexact, unreliable, untrustworthy
Antonyms
1 constant, faithful, loyal, steadfast, true, trustworthy
3 accurate, exact, perfect, precise, reliable