infallible

"Fallible" means capable of making mistakes — or, easier to remember — capable of failing. Infallible means exactly the opposite — incapable of failing.

This word is often used to describe human capacity for error — no one is infallible. And yet, we are able to be infallible in certain ways: children are infallibly curious, teenagers infallibly hungry. Interestingly, infallible derives from the Latin in- "not" + fallere "deceive." When did making a mistake and deception become the same thing?

Definitions of infallible
  1. adjective
    incapable of failure or error
    “an infallible antidote”
    “an infallible memory”
    “no doctor is infallible
    Synonyms:
    foolproof, unfailing
    not liable to failure
    inerrable, inerrant, unerring
    not liable to error
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    Antonyms:
    fallible
    likely to fail or make errors
    errant
    straying from the right course or from accepted standards
    erring, error-prone
    capable of making an error
    undependable, unreliable
    liable to be erroneous or misleading
    weak
    likely to fail under stress or pressure
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