"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

adj incapable of failure or error

“an infallible antidote”
“an infallible memory”
“the Catholic Church considers the Pope infallible
“no doctor is infallible
foolproof, unfailing
not liable to failure
inerrable, inerrant, unerring
not liable to error
likely to fail or make errors
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
likely to fail under stress or pressure
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