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A security feature, as on a webpage, that attempts to distinguish between legitimate human users and bots by requiring users to perform a mildly challenging task such as deciphering distorted text.
[Acronym of c(ompletely) a(utomated) p(ublic) T(uring test to tell) c(omputers and) h(umans) a(part), coined in 2000 by the researchers who developed the security feature and intended to suggest a colloquial pronunciation of capture.]
(Communications & Information) a test in which the user of a website is asked to decipher a distorted image, used to protect the website against automated attacks
[C21: acronym for C(ompletely) A(utomated) P(ublic Turing Test to) T(ell) C(omputers and) H(umans) A(part)]