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See also: captcha and Captcha


A typical representation of a CAPTCHA

Alternative forms[edit]


Coined by a team of researchers at Carnegie Mellon University in 2000 as a loose acronym of “completely automated public Turing test to tell computers and humans apart”.




  1. A computerized test requiring the human user to perform a task deemed to be difficult to automate, such as entering a displayed series of distorted characters or describing images, to demonstrate that he/she is a human and not a computer program.
    • 2011, Dafydd Stuttard, Marcus Pinto, The Web Application Hacker's Handbook: Finding and Exploiting Security Flaws, John Wiley & Sons (→ISBN)
      CAPTCHA puzzles are intended to be easy for a human to solve but difficult for a computer. Because of the monetary value to spammers of circumventing these controls, an arms race has occurred in which typical CAPTCHA puzzles have []
    • 2014, Laura Fitton, Anum Hussain, Brittany Leaning, Twitter For Dummies, John Wiley & Sons (→ISBN), page 24:
      A CAPTCHA is a quick check to make sure that an actual person, rather than a computer program, is using the website. Web applications use CAPTCHA []

Usage notes[edit]

Although occasionally spelt with lowercase letters (captcha), or with an initial uppercase letter (Captcha), most authors remain aware of its origin as an acronym and use uppercase.


See also[edit]

Further reading[edit]



Borrowed from English.


CAPTCHA m (plural CAPTCHA's)

  1. Alternative letter-case form of captcha