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

You might wonder how these products work and whether they're foolproof enough to put the fear of bleeding through your clothes at bay.

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As suppliers scramble to call new vendors or reroute supply lines, it’s clear that no one has a foolproof plan.

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But there is one foolproof sign that groundwater is disappearing: The earth above it collapses as the ground compresses like a drying sponge.

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David Bolt, the Independent Chief Inspector of Borders and Immigration, said the absence of a "foolproof test" of age it was "inevitable that some age assessments will be wrong".

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The second question on this foolproof rubric is, “Does the shark movie have a necessary degree of camp that both reveres and respects that it is, indeed, a shark movie?”

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Related Words

• flawless 
• reliable 
• surefire 
• unassailable