infallible
Americanadjective
-
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
adjective
-
not fallible; not liable to error
-
not liable to failure; certain; sure
an infallible cure
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completely dependable or trustworthy
noun
Related Words
See reliable.
Other Word Forms
- infallibility noun
- infallibleness noun
- infallibly adverb
- noninfallible adjective
- noninfallibly adverb
Etymology
Origin of infallible
First recorded in 1375–1425; late Middle English word from Medieval Latin word infallibilis. See in- 3, fallible
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
They are never infallible or immune to misjudgment.
From Slate • Feb. 16, 2026
They aren't infallible but they will increase the hassle factor for criminals.
From BBC • Feb. 7, 2026
Dimon also said Tuesday that he didn’t think the Fed was infallible and had made mistakes.
From The Wall Street Journal • Jan. 13, 2026
To be sure, the “lipstick index” was never infallible, or even very popular, as far as economic theories go.
From MarketWatch • Dec. 12, 2025
But since in reality Big Brother is not omnipotent and the Party is not infallible, there is need for an unwearying, moment-to-moment flexibility in the treatment of facts.
From "1984" by George Orwell
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
