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.
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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.
But it does make clear that AI isn’t magic, nor are those who are making and marketing it infallible.
From Los Angeles Times • Mar. 26, 2026
They are never infallible or immune to misjudgment.
From Slate • Feb. 16, 2026
The Citrus Heights Police Department chief declined to comment specifically on the case but said that while the citation process isn’t infallible, all individuals who get a summons receive due process.
From The Wall Street Journal • Dec. 28, 2025
To be sure, the “lipstick index” was never infallible, or even very popular, as far as economic theories go.
From MarketWatch • Dec. 12, 2025
Notwithstanding that the devil, played by Cook, gives himself away at once by wearing red socks, the infallible mark of a cad, Dudley falls into conversation with him.
From "Words Like Loaded Pistols" by Sam Leith
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.
