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

Two different kinds of potatoes and the foolproof combo of seasonings will see you through this recipe. — Patricia S York, Southern Living, 27 June 2026

This all sounds impressive enough, but even futuristic weapons like lasers are not foolproof on the battlefield. — Christopher McFadden, Interesting Engineering, 20 June 2026

Sundresses are also a foolproof staple for summer. — Clara McMahon, PEOPLE, 26 June 2026

There are several potential solutions, but none are foolproof. — John Romano, The Orlando Sentinel, 29 June 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