Emily Dickinson Lexicon

IN-FAL'LI-BLE, a. [Fr. infaillible; in and faillir, L. fallo.]

1. Not fallible; not capable of erring; entirely exempt from liability to mistake; applied to persons. No man is infallible; to be infallible is the prerogative of God only.
2. Not liable to fail, or to deceive confidence; certain; as, infallible evidence; infallible success. To whom he showed himself alive after his passion, by many infallible proofs. Acts i.