Main Entry: in·fal·li·ble

Pronunciation: \(ˌ)in-ˈfa-lə-bəl\

Function: adjective

Etymology: Middle English, from Medieval Latin infallibilis, from Latin in- + Late Latin fallibilis fallible

Date: 15th century

1 : incapable of error : unerring <an infallible memory>
2 : not liable to mislead, deceive, or disappoint : certain <an infallible remedy>
3 : incapable of error in defining doctrines touching faith or morals

— in·fal·li·bil·i·ty \-ˌfa-lə-ˈbi-lə-tē\ noun

— in·fal·li·bly \-ˈfa-lə-blē\ adverb