foolproof
Americanadjective
-
involving no risk or harm, even when tampered with.
-
never-failing.
a foolproof method.
adjective
-
proof against failure; infallible
a foolproof idea
-
(esp of machines) proof against human misuse, error, etc
Etymology
Origin of foolproof
Explanation
When something is bound to work out, you can call it foolproof. Your foolproof plan for having a great summer might involve spending lots of time at the beach. If your dog tends to wander and can also jump six feet in the air, a foolproof plan for keeping her in your yard might involve an eight foot fence. You can also use foolproof as a verb: "I'm going to foolproof the instructions for heating up your dinner, so that no one sets the stove on fire this time." Foolproof is an early twentieth century American English word that combines fool, or "silly person" and proof, "resistant."
Vocabulary lists containing foolproof
Game Changer
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Old Yeller
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The Bad Beginning
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
A foolproof strategy for redeeming credit-card points on flights or hotels?
From MarketWatch ● Aug. 11, 2026
He said Modi had called for a "foolproof system" to prevent irregularities in the future at a closed-door meeting with his allies on Tuesday.
From Barron's ● Jul. 21, 2026
Not that it was foolproof, but it was just such a silly idea and I was a fan of David Wain and those guys anyway.
From Los Angeles Times ● Jul. 6, 2026
An airport might try to capture an aircraft’s tail number via photography, though that method is hardly foolproof.
From The Wall Street Journal ● Jun. 17, 2026
“Surely you didn’t think you could fool my Whisperer. How typically juvenile. I’m afraid my Whisperer is foolproof, Reynard. Or perhaps I should say childproof—they amount to the same thing.”
From "The Mysterious Benedict Society" by Trenton Lee Stewart
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
