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

Daniels has been infallible in the postseason, beating every scheme and exposing every defensive trick. —J.j. Bailey, The Athletic, 21 Jan. 2025

Checkers are not infallible, and their successes are mostly due to hard work and creativity. —Fergus McIntosh, The New Yorker, 11 Jan. 2025

The private school, Feather River Adventist School, is affiliated with the Seventh-day Adventist Church, part of the Protestant Christian denomination whose followers believe the Bible is the infallible word of God and in the second coming of Christ. —Karina Tsui, Holly Yan and Nicole Chavez, CNN, 17 Dec. 2024

Over jackets, over dresses, over other sweaters or even over your favorite coat, the simplest and most everyday action becomes an infallible trick to elevate an outfit. —Teresa Romero Martínez, Glamour, 8 Dec. 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