(1):
(a.) Not fallible; not capable of erring; entirely exempt from liability to mistake; unerring; inerrable.
(2):
(a.) Not liable to fail, deceive, or disappoint; indubitable; sure; certain; as, infallible evidence; infallible success; an infallible remedy.
(3):
(a.) Incapable of error in defining doctrines touching faith or morals. See Papal infallibility, under Infallibility.