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

One of the most foolproof ways to know when severe weather is en route or likely to form is simply to have your smartphone. —Cody Godwin, USA Today, 23 Apr. 2025

Wear them together for a foolproof spring outfit, or separately with dressier or more casual pieces in your suitcase, depending on the occasion. —Amelia McBride, Travel + Leisure, 21 Mar. 2025

While no security measure is completely foolproof, combining these practices can significantly reduce the risk of falling victim to infostealer malware. —Kurt Knutsson, Cyberguy Report, Fox News, 26 Feb. 2025

How To Make It This is truly one of the easiest and most foolproof meals out here. —Cameron Beall, Southern Living, 17 Feb. 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