infallible

[ in-fal-uh-buhl ]

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

/ ɪnˈfæləbəl /

adjective

1. not fallible; not liable to error
2. not liable to failure; certain; sure

   an infallible cure

3. completely dependable or trustworthy

noun

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

Derived Forms

• inˈfallibly, adverb
• inˌfalliˈbility, noun

Other Words From

• 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

Word History and Origins

Origin of infallible¹

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

Synonym Study

See reliable.

Example Sentences

Trailing has been far more effective for Boston than switching in the Finals, yet it isn’t infallible.

From FiveThirtyEight

The work is a reminder that no matter how elegant or infallible mathematics may seem, it’s still a human endeavor.

From Science News

Their men on horseback — Theodore Roosevelt, Grant, even Washington — were not regarded as infallible.

From Washington Post

Even if he is, though, the pope may be infallible, but he is not omnipotent.

From The Daily Beast

Besides Diamond, some of the Saved By the Bell characters are portrayed as infallible angels.

From The Daily Beast

As long as they believed Saraswati was infallible, any dissatisfaction they experienced was a personal shortcoming.

From The Daily Beast

Buffett is not infallible and his hiding in the bunker does not make him appear stronger, wiser, or accountable.

From The Daily Beast

To the vast majority of the devout, Pope Benedict XVI is infallible and the church has done nothing wrong.

From The Daily Beast

"Doa Estefania, have no fear; you possess an infallible preservative," exclaimed the cappellan.

From Project Gutenberg

When Dan put his tobacco back unbitten, it was always an infallible sign that something had gone in a way that did not suit him.

From Project Gutenberg

An infallible method of remembering proper names is Get the name when introduced.

From Project Gutenberg

But Ramona saw now, with infallible intuition, that even as she had loved Alessandro, so Felipe loved her.

From Project Gutenberg

This may be said to be an infallible rule, and an examination of the instruments of the most celebrated makers fully confirms it.

From Project Gutenberg

Related Words

• authoritative
• flawless
• foolproof
• unbeatable