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

Worcestershire, dry mustard, and ground red pepper combine with your go-to cheese, for a foolproof party snack. —Mary Alice Russell, Southern Living, 22 Oct. 2025

The company makes an effort to remove underage accounts when discovered and limit access to adult-only servers (for those 18 years and older), but experts note that these protections are not foolproof. —Alex Vance, Parents, 21 Oct. 2025

There’s no foolproof answer, except perhaps to bring expensive items inside at night. —Marla Jo Fisher, Oc Register, 14 Oct. 2025

This chocolate Advent calendar is a foolproof Christmas gift for teenagers of all ages, with its 24 days of delicious milk chocolate Lindt balls and teddy bears. —Malia Griggs, Glamour, 9 Oct. 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