infallible Synonyms

faultless perfect inerrant unequivocal undisputable trusty trustworthy true ten sure secure satisfying safe right returnless unmistaken unerring unflawed tried and true surefire sure-fire establishable error-free errorless foolproof confirmed fail-safe a-okay unquestionable unfailing reliable precise positive effective dependable definite correctible correct conclusive certain categorical assured apodictic accurate acceptable efficacious exact faithful omniscient necessary