Synonyms of infallible

infallible

adjective

(ˌ)in-ˈfa-lə-bəl 

1

as in unerring

not being or likely to be wrong

a teacher with an infallible memory for names

Synonyms & Similar Words

• unerring
• perfect
• reliable
• flawless
• unfailing
• foolproof
• faultless
• impeccable
• dependable
• inerrant
• sure
• errorless
• certain

Antonyms & Near Antonyms

• defective
• imperfect
• faulty
• fallible
• flawed
• unreliable
• undependable

2

as in reliable

not likely to fail

an infallible cure for hiccups

Synonyms & Similar Words

• reliable
• unfailing
• sure
• fail-safe
• surefire
• certain
• dependable
• deadly
• can't-miss
• unerring

Antonyms & Near Antonyms

• fallible
• uncertain
• doubtful
• questionable

Example Sentences

Recent Examples of infallible

These words are also coming from a former priest, a man the world is taught to believe is infallible simply because of his profession. — Whitney Friedlander, Variety, 6 Aug. 2026

Bash, Tapper, CNN and many others treated Fauci as an infallible god. — Ian Miller Outkick, FOXNews.com, 3 Aug. 2026

Not that the Coastal Commission has been infallible over the years. — Steve Lopez, Los Angeles Times, 11 July 2026

Both experts acknowledged that the tests are not infallible, can’t determine exactly when DNA was left on an item, and can't confirm the source of DNA with absolute certainty. — N'dea Yancey-Bragg, USA Today, 10 July 2026