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

Adding a preppy cardigan over a white tee and a pair of jeans is a foolproof formula that always works, but the sartorial possibilities of this breed of knitwear go far beyond that. — Camille Freestone, Glamour, 10 Sep. 2026

If the premise is that for the Commanders to excel, Daniels needs to excel — and that’s a pretty foolproof premise — then Blough’s ability to keep his quarterback out of danger and maximize his extraordinary abilities is paramount. — Barry Svrluga, New York Times, 9 Sep. 2026

The short answer is that there is no foolproof method, because successful manipulation depends precisely on making self-serving behavior seem prosocial. — Tomas Chamorro-Premuzic, Forbes.com, 29 Aug. 2026

One foolproof way to do as the Germans do is to wear their brands. — Carolin Lehmann, Travel + Leisure, 23 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