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Synonyms

infallible

American  
[in-fal-uh-buhl] / ɪnˈfæl ə bəl /

adjective

  1. absolutely trustworthy or sure.

    an infallible rule.

  2. unfailing in effectiveness or operation; certain.

    an infallible remedy.

  3. not fallible; exempt from liability to error, as persons, their judgment, or pronouncements.

    an infallible principle.

  4. 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

  1. an infallible person or thing.

infallible British  
/ ɪnˈfæləbəl /

adjective

  1. not fallible; not liable to error

  2. not liable to failure; certain; sure

    an infallible cure

  3. completely dependable or trustworthy

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. a person or thing that is incapable of error or failure

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Related Words

See reliable.

Other Word Forms

Etymology

Origin of infallible

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

Explanation

"Fallible" means capable of making mistakes — or, easier to remember — capable of failing. Infallible means exactly the opposite — incapable of failing. This word is often used to describe human capacity for error — no one is infallible. And yet, we are able to be infallible in certain ways: children are infallibly curious, teenagers infallibly hungry. Interestingly, infallible derives from the Latin in- "not" + fallere "deceive." When did making a mistake and deception become the same thing?

Keep Reading on Vocabulary.com

Vocabulary lists containing infallible

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.

Two Bit wasn’t ready to discuss the latter, stopping the tour instead inside the bridge of a ship that was called the Space Squad Infallible.

From Los Angeles Times • Jul. 23, 2018

Better still, Penzler resurrects many hard-to-come-by stories, notably Stuart Towne’s novella “Death Out of Thin Air” and one of Frederick Irving Anderson’s accounts of the Infallible Godahl.

From Washington Post • Dec. 10, 2014

This week, with the American publication of his blunt book Infallible?

From Time Magazine Archive

Infallible Fallacies, by "Some Priests of the Anglican Communion," is a closely reasoned piece of polemic in a venerable but almost forgotten tradition.

From Time Magazine Archive

Brigid brought more soup from her now fully recovered mother and a half bottle of Dr. Rush’s Infallible Health Pills.

From "Lyddie" by Katherine Paterson