infallible

1 of 2

adjective

Synonyms of infallible
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

infallibility

2 of 2

noun

: the quality or state of being infallible

Did you know?

Watch out when you hear about infallible predictions, an infallible plan, an infallible cure, or even infallible lip gloss. Infallible isn't a claim that scientists, engineers, and doctors like to make, so you're probably getting better information when the word not comes first. You may have heard the phrase "papal infallibility", which refers to the official position of the Roman Catholic church, adopted in the 19th century, that certain solemn statements made by a Pope about faith or morals were not to be questioned. Popes since then have been careful not to make many of these statements.

Examples of infallible in a Sentence

Adjective I never claimed to be infallible. There is no infallible remedy to these problems.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Adjective
Not that the Coastal Commission has been infallible over the years. Steve Lopez, Los Angeles Times, 11 July 2026 Both experts acknowledged that the tests are not infallible, can’t determine exactly when DNA was left on an item, and can't confirm the source of DNA with absolute certainty. N'dea Yancey-Bragg, USA Today, 10 July 2026 The government’s data are far from infallible (and, as history has shown, can be manipulated). Will Gottsegen, The Atlantic, 9 July 2026 Corporate governance solutions rarely come in the form of universal, infallible prescriptions. Jeffrey Sonnenfeld, Fortune, 6 July 2026 See All Example Sentences for infallible

Word History

Etymology

Adjective

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

Noun

Medieval Latin infallibilitas, from infallibilis infallible + Latin -itas -ity

First Known Use

Adjective

15th century, in the meaning defined at sense 1

Time Traveler
The first known use of infallible was in the 15th century

Browse Nearby Words

Cite this Entry

“Infallible.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infallible. Accessed 15 Jul. 2026.

Kids Definition

infallible

adjective
1
: not capable of being wrong : unerring
an infallible memory
2
: not likely to fail : sure
an infallible remedy

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