foolproof

adjective

fool·​proof ˈfül-ˌprüf 

: 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

But, as anyone who’s watched an icy soda turn watery on a summer day can probably gather, moving hard ice to warm climates wasn’t exactly foolproof. — Mack Degeurin, Popular Science, 19 Aug. 2026

First, the cream-to-powder texture is foolproof—the edges smoke out with the slightest tap, making blending a dream. — Kiana Murden, Vogue, 17 Aug. 2026

Gap Linen Oversized Shirt Linen is a foolproof material every Euro summer traveler should pack in their suitcase. — Julia Morlino, Travel + Leisure, 17 Aug. 2026

The foolproof outfit formula simplifies everyday dressing and delivers double the styling options. — Kyra Surgent, InStyle, 15 Aug. 2026

Word History

First Known Use

1874, in the meaning defined above

Rhymes for foolproof

• aloof
• behoof
• disproof
• flameproof
• greaseproof
• leakproof
• reproof
• soundproof
• bulletproof
• fireproof
• waterproof
• weatherproof

Kids Definition

foolproof

adjective

fool·​proof ˈfül-ˈprüf 

: done, made, or planned so well that nothing can go wrong

foolproof directions