infallible

adjective

in·​fal·​li·​ble (ˌ)in-ˈfa-lə-bəl 

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

(ˌ)in-ˌfa-lə-ˈbi-lə-tē 

noun

infallibly

(ˌ)in-ˈfa-lə-blē 

adverb

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.

Synonyms

• unerring
• unfailing

Examples of infallible in a Sentence

I never claimed to be infallible.

There is no infallible remedy to these problems.

Recent Examples on the Web

And these heroes, slightly idealized but by no means infallible versions of the ones who exist in real hospitals, keep showing up, shift after endless shift, to keep pushing that rock up the hill. —Judy Berman, Time, 11 Apr. 2025

Many treat data as infallible, ignoring context, sampling biases, and statistical significance. —Scott White, Forbes.com, 28 Mar. 2025

Advanced Navigation View 2 Images Even though most of today's aircraft rely heavily on GPS for navigation, the technology is far from infallible. —Ben Coxworth, New Atlas, 4 Dec. 2024

Authentic leadership fosters trust and connection, yet many leaders feel compelled to hide behind an infallible persona. —Imamu "mu" Tomlinson, Forbes, 24 Feb. 2025

Word History

Etymology

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

First Known Use

15th century, in the meaning defined at sense 1

Rhymes for infallible

• fallible

Kids Definition

infallible

adjective

in·​fal·​li·​ble (ˈ)in-ˈfal-ə-bəl 

1

: not capable of being wrong : unerring

an infallible memory

2

: not likely to fail : sure

an infallible remedy

infallibility

(ˌ)in-ˌfal-ə-ˈbil-ət-ē 

noun

infallibly

(ˈ)in-ˈfal-ə-blē 

adverb