What does "infallible" mean?

Infallible: Not liable to fail, deceive, or disappoint; indubitable; sure; certain; as, infallible evidence; infallible success; an infallible remedy. To whom also he showed himself alive, after his passion, by many infallible proofs. Acts i.

Additional senses

  1. 2.3. (R. C. Ch.) Incapable of error in defining doctrines touching faith or morals. See Papal infallibility, under Infallibility.

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