infallible

[ in-fal-uh-buh l ]
/ ɪnˈfæl ə bəl /

adjective

absolutely trustworthy or sure: an infallible rule.
unfailing in effectiveness or operation; certain: an infallible remedy.
not fallible; exempt from liability to error, as persons, their judgment, or pronouncements: an infallible principle.
Roman Catholic Church. immune from fallacy or liability to error in expounding matters of faith or morals by virtue of the promise made by Christ to the Church.

noun

an infallible person or thing.

Origin of infallible

First recorded in 1375–1425; late Middle English word from Medieval Latin word infallibilis. See in-3, fallible

SYNONYMS FOR infallible

1, 2 See reliable.

OTHER WORDS FROM infallible

in·fal·li·bil·i·ty, in·fal·li·ble·ness, noun in·fal·li·bly, adverb non·in·fal·li·ble, adjective non·in·fal·li·bly, adverb

Example sentences from the Web for infallible

British Dictionary definitions for infallible

infallible
/ (ɪnˈfæləbəl) /

adjective

not fallible; not liable to error
not liable to failure; certain; sure an infallible cure
completely dependable or trustworthy

noun

a person or thing that is incapable of error or failure

Derived forms of infallible

infallibility or infallibleness, noun infallibly, adverb