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
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Old Yeller
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
The Bad Beginning
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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 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
Now Huffington jokes that she has a foolproof plan to ensure that the Knicks will clinch their first championship in 53 years on Saturday night in San Antonio.
From The Wall Street Journal ● Jun. 11, 2026
But the Dutch blueprint isn't foolproof - youth unemployment is rising.
From BBC ● Jun. 7, 2026
That isn’t to say the system is foolproof.
From Los Angeles Times ● May 7, 2026
“Can you make a one hundred percent foolproof app that helps people find their soul mate?”
From "What If It's Us" by Becky Albertalli and Adam Silvera
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.
