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.
He’d come armed with a time-honored, foolproof strategy: an offer Seinfeld couldn’t refuse.
From The Wall Street Journal ● Oct. 23, 2026
“I don’t think there’s any foolproof method of dealing with cognitive decline or fraud where the person truly believes what’s being told to them,” said Anspach.
From MarketWatch ● Sep. 24, 2026
Although no preparation is foolproof, there are steps you can take to reduce risks at home and on the road.
From Los Angeles Times ● Sep. 22, 2026
Police will review policy and processes to ensure protocols are "foolproof" into the future, Lanyon added.
From BBC ● Aug. 21, 2026
This was usually a foolproof comeback, making up in scorn what it lacked in originality, but on this occasion it backfired.
From "The Glass Castle" by Jeannette Walls
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Get a wordDefinitions 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.
