foolproof

[fool-proof]

adjective

1. involving no risk or harm, even when tampered with.

2. never-failing.

   a foolproof method.

foolproof

/ ˈfuːlˌpruːf /

adjective

1. proof against failure; infallible

   a foolproof idea

2. (esp of machines) proof against human misuse, error, etc

Word History and Origins

Origin of foolproof¹

An Americanism dating back to 1900–05; fool ¹ + -proof

Example Sentences

Her plan to get back to Ashton Place and the Incorrigible children was in no way foolproof.

Read more on Literature

It was because her plan about the séance, which had seemed so simple and foolproof when she first thought of it, now appeared to have more holes in it than a mole-infested garden.

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It was hardly foolproof; indeed, it was almost certain to fail more often than it succeeded.

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The president and chief investment officer of Alphabet and Google shares her foolproof B.S. detector and why big tech can be like playing with fire.

Read more on The Wall Street Journal

But, Coffee warned, “AI is not foolproof and they don’t have the same depth of knowledge at least initially as the Big Four.”

Read more on The Wall Street Journal

Related Words

• flawless 
• reliable 
• surefire 
• unassailable