foolproof

adjective

fool·​proof ˈfül-ˌprüf How to pronounce foolproof (audio)
: so simple, plain, or reliable as to leave no opportunity for error, misuse, or failure
a foolproof plan

Examples of foolproof in a Sentence

DNA fingerprinting gives police a virtually foolproof way to link a suspect to a crime scene.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Ultrasounds, though highly accurate, are not foolproof. Daniella Gray, MSNBC Newsweek, 1 Sep. 2025 But, there are some foolproof ways to choose a sensory-friendly paint color. Shivani Vyas, Better Homes & Gardens, 27 Aug. 2025 But forgetting is foolproof if your water bottle is always slung around your neck. Anna Fiorentino, Travel + Leisure, 21 Aug. 2025 Turn your favorite breakfast duo into a filling casserole with this foolproof recipe. Mary Shannon Wells, Southern Living, 18 Aug. 2025 See All Example Sentences for foolproof

Word History

First Known Use

1874, in the meaning defined above

Time Traveler
The first known use of foolproof was in 1874

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Cite this Entry

“Foolproof.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/foolproof. Accessed 10 Sep. 2025.

Kids Definition

foolproof

adjective
fool·​proof ˈfül-ˈprüf How to pronounce foolproof (audio)
: done, made, or planned so well that nothing can go wrong
foolproof directions

More from Merriam-Webster on foolproof

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