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[kap-chuh] /ˈkæp tʃə/
noun, Digital Technology.
an online test designed so that humans but not computers are able to pass it, used as a security measure and usually involving a visual-perception task:
Site visitors must solve the “distorted text” CAPTCHA before posting comments.
a computer program that generates such tests.
Origin of CAPTCHA
2000-05; C(ompletely) A(utomated) P(ublic) T(uring) (Test to Tell) C(omputers and) H(umans) A(part) Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for CAPTCHA
Contemporary Examples
  • Called "CAPTCHA," it's essentially a test that's easy for a human to complete, but difficult or impossible for a computer to do.

Contemporary definitions for CAPTCHA

a computer-generated squiggly-letter test that must be typed in by Internet/Web users to prove they are human


In order to send an email about a New York Times article, the site makes you type in a captcha.

Word Origin

by 2001; acronym for Completely Automatic Public Turing test to tell Computers and Humans Apart's 21st Century Lexicon
Copyright © 2003-2014, LLC
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CAPTCHA in Technology

A type of test used to determine whether a request to a web site comes from a human or a computer program, typically by asking the user to perform some kind of image recognition task such as reading distorted text. The term was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper (all of Carnegie Mellon University) and John Langford (of IBM) as a contrived acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart". CAPTCHA aims to prevent software tools from performing actions which might degrade the service, such as registering user accounts or automating the playing of a game.

The Free On-line Dictionary of Computing, © Denis Howe 2010
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