infallible

/ɪnˈfæləbəl/

/ɪnˈfælɪbəl/

Other forms: infallibly

"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

   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