unfailing

1 not being or likely to be wrong <an unfailing judge of personal character> Synonyms unerring, infallibleRelated Words errorless, faultless, flawless, impeccable; certain, foolproof, inerrant, perfect, sure; dependable, reliableNear Antonyms defective, faulty, flawed, imperfect; undependable, unreliableAntonyms fallible

2 not likely to fail <the writer's unfailing sense of humor is again evident in his newest book> Synonyms can't-miss, certain, fail-safe, sure, surefire, infallibleRelated Words dependable, reliable; deadly, unerringNear Antonyms doubtful, questionable, uncertainAntonyms fallible