involving no risk or harm, even when tampered with.
never-failing: a foolproof method.

Origin of foolproof

An Americanism dating back to 1900–05; fool1 + -proof Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for foolproof

Contemporary Examples of foolproof

Historical Examples of foolproof

  • All of us—all the Academy top brass—develop a foolproof test for cadet maneuvers.

    Stand by for Mars!

    Carey Rockwell

  • He had to establish some sort of foolproof disguise, and he had to make contact with Earth's underground.

  • There are a few sequences of words that really are foolproof, carrying their own atmosphere and dignity with them.

    The Book of Susan

    Lee Wilson Dodd

  • He had smashed the radio, a marvelously compact and foolproof outfit, arbitrarily tuned to a fixed short wave-length.

  • This time he wasn't afraid of meeting a Bandersnatch or anything else, for he had a method of escape that was foolproof.


    Jesse Franklin Bone

British Dictionary definitions for foolproof



proof against failure; infalliblea foolproof idea
(esp of machines) proof against human misuse, error, etc
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for foolproof

also fool-proof, 1902, American English, "safe against the incompetence of a fool," from fool (n.) + proof.

Online Etymology Dictionary, © 2010 Douglas Harper