INFALLIBLE

adj not fallible; not capable of erring; entirely exempt from liability to mistake; unerring; inerrable.

2. infallible ·adj incapable of error in defining doctrines touching faith or morals. ·see papal infallibility, under infallibility.

3. infallible ·adj not liable to fail, deceive, or disappoint; indubitable; sure; certain; as, infallible evidence; infallible success; an infallible remedy.