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, 29 Sep. 2025

While traditional bread is foolproof option, Atlas recommends giving focaccia a try instead (sourdough is so 2020). —Cori Sears, Better Homes & Gardens, 29 Sep. 2025

The only foolproof way to fully kill bacteria on your greens, per Gavin? —Danielle Zickl, Health, 26 Sep. 2025

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

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