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

While not foolproof – replication failures can occur due to human error, inaccurate details of study design and many other variables that may be difficult to control for – results that remain unproven are a huge red flag. —New Atlas, 24 Sep. 2025

None of this, of course, provides a foolproof hedge against the risk of Trump making concessions on Taiwan in exchange for a trade deal or a better relationship with Xi. —Philip H. Gordon, Foreign Affairs, 22 Sep. 2025

Available in four natural-looking shades that are neither too red nor too gray, this whisper-soft powder offers a foolproof way to accentuate your arches and create the illusion of fullness without the reality of smudges or streaks. —Sophia Panych, Allure, 16 Sep. 2025

The old-fashioned casserole is a foolproof recipe with simple ingredients, but packed with flavor. —Cameron Beall, Southern Living, 16 Sep. 2025

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