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

Dimon also said Tuesday that he didn’t think the Fed was infallible and had made mistakes.

From The Wall Street Journal • Jan. 13, 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

It works, and for what it is designed to accomplish it is as infallible as anything in nature.

From "The Lives of a Cell" by Lewis Thomas