infallible

[in-fal-uh-buhl] / ɪnˈfæl ə bəl /

ADJECTIVE

unerring, dependable

Synonyms

STRONGEST

authoritative flawless foolproof unbeatable

WEAK

acceptable accurate agreeable apodictic certain correct effective effectual efficacious efficient exact faultless handy helpful impeccable incontrovertible inerrable inerrant omniscient perfect positive reliable satisfactory satisfying sure surefire true trustworthy undeceivable unfailing unimpeachable unquestionable useful

Antonyms

WEAK

erring fallible faulty imperfect

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

They are never infallible or immune to misjudgment.

From Slate • Feb. 16, 2026

They aren't infallible but they will increase the hassle factor for criminals.

From BBC • Feb. 7, 2026

To be sure, the “lipstick index” was never infallible, or even very popular, as far as economic theories go.

From MarketWatch • Dec. 12, 2025

And a few moments of self-doubt for our seemingly infallible sleuth.

From The Wall Street Journal • Oct. 2, 2025

Clara realized that that was why none of her infallible methods of divining had worked.

From "The House of the Spirits: A Novel" by Isabel Allende