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

That the Panthers came that close revealed the limitations of an Eagles defense that isn’t infallible. —Brooks Kubena, The Athletic, 9 Dec. 2024

While there are notable and beautiful bright spots to All or Nothing (most of which go to infallible Leigh regular Ruth Sheen), the film really doubles down on the ambient misery of these people’s lives. —Fran Hoepfner, Vulture, 9 Dec. 2024

These agents shift human roles from task execution to oversight, freeing up time for strategic and creative work. Trust and Guardrails Despite their potential, AI agents are not infallible. —Charles Towers-Clark, Forbes, 29 Nov. 2024

Elsbeth spins off another Good Wife character, Carrie Preston's Elsbeth Tascioni, a quirky attorney whose idiosyncratic methods and infallible intuition land her a unique gig assisting the NYPD on hard-to-crack cases. —Ryan Coleman, EW.com, 26 Nov. 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