infalible

Infalible is a term whose primary meaning is “not liable to fail” or “incapable of making mistakes.” In English, the standard spelling is infallible. The form infalible is usually a misspelling, though it appears in translations from Romance languages and in some proper names or brand names.

Etymology and sense: Infalible derives from Latin infallibilis, formed with in- meaning “not” and fallibilis from fallere, meaning “to deceive” or “to err.” The sense of being unable to err or to be deceived underpins both the English infallible and the cognate forms in other languages.

Romance-language forms: In Spanish, infalible means infallible; Italian uses infalibile; Portuguese uses infalível. In these languages the word is standard and correctly spelled, while English consistently uses infallible. The Romance forms are etymologically related and share the same core meaning.

Usage in theology and philosophy: In secular use, infallible is often reserved for something deemed unquestionably reliable. In religious contexts, infallibility refers to a lack of error in matters of faith and morals. A well-known contemporary example is papal infallibility, a doctrine established during the First Vatican Council, which holds that the pope is free from error when defining faith or morals ex cathedra.

See also: infallibility, fallibility, papal infallibility.