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

Denver’s not infallible by any stretch, but it’s played well on defense and special teams most of the season, and the run game has ramped up in recent weeks. —Matt Schubert, The Denver Post, 27 Oct. 2024

No one is infallible, of course, and a desire to hold people accountable could be taken too far. —Stephen M. Walt, Foreign Affairs, 16 Apr. 2019

Unfortunately, lots of people these days try to quote AI as though the AI is infallible. —Lance Eliot, Forbes, 22 Oct. 2024

The trick is not infallible: Lawrence’s mid-2000s comedy Undateable began as the story of a player teaching a nerd how to talk to women, and (again) very quickly pivoted into a hangout comedy about their appealing friends from a bar. —Alan Sepinwall, Rolling Stone, 15 Oct. 2024

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

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