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definition of CAPTCHA (also captcha)
nounan acronym which describes a program that protects websites from spammers by providing a test (e.g. a distorted text) which humans can do but computers cannot. It stands for 'Completely Automated Public Turing Test To Tell Computers and Humans Apart' and is a trademark of Carnegie Mellon University. There are visual as well as audio captchas in use.
Recognising the kinds of characters used in CAPTCHAs remains a significant challenge in computer vision.
Submitted on 28/09/2009 09:37:00
Definition of CAPTCHA (also captcha) from the Open Dictionary – a public resource hosted by Macmillan English Dictionary Online
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