from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Designed so as to be impervious to human incompetence, error, or misuse: a foolproof detonator; a foolproof safety lock.
  • adj. Effective; infallible: a foolproof scheme.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. For a device: protected, or designed to be proof against misuse or error; fail-safe.
  • adj. For an idea or plan: infallible, or bulletproof.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. not liable to failure
  • v. proof against human misuse or error


fool +‎ -proof (Wiktionary)


  • “A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.”

    EXTRALIFE – By Scott Johnson - Codery Quotations

  • Curse that Aimee and her so-called foolproof formula for success: “Wear your hair down and the highest heels you have, then watch the tips roll in.”

    Fashionably Late

  • The little formulas that the smart boys who design these so-called foolproof systems build in so they can sneak a gander whenever they feel like it.

    Tek Money

  • He proceeded to share his so-called foolproof secrets on how he managed to purchase eleven cars in his lifetime way below sticker price. News

  • There is nothing which can be called foolproof or completely safe.

    Propeller Most Popular Stories

  • However, mammograms as important as they are, are not 100\% foolproof, which is why a CBE by a trained examiner is strongly recommended.

    Phoenix Arizona Real Estate Local News and Business Directory

  • Look, I'm not an expert, but I am a bit skeptical that we could invent some kind of foolproof shield to stop a bunch of nukes.

    The 21st Century's Gonna Suck Big-Time

  • "I'd like to have close cooperation with the United States, but in tenders I prefer a good price and good quality," Mr. Schwarzenberg said, adding that only a "foolproof" safety design would be acceptable.

    Czechs Weighs Alternatives to Russian Energy

  • Forget "foolproof" technology — we need systems designed to fail smartly

    The Things He Carried

  • What do you think about Google Doc's security, especially when it comes to how "foolproof" the app is?

    Wired Top Stories

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  • even an Idiot can do it
    Sure to be successful

    May 27, 2009

  • That which usually proves not to be.

    September 15, 2008