capt·​cha ˈkap-chə How to pronounce captcha (audio)
variants or CAPTCHA
: a test to prevent spamming software from accessing a website by requiring visitors to the site to solve a simple puzzle (typically by reading and transcribing a series of numbers or letters from a distorted image) in order to gain access
The point of the CAPTCHA is that reading those swirly letters is something that computers aren't very good at. If you can read them, you're probably not a piece of software run by a spammer.Lev Grossman

Examples of captcha in a Sentence

Recent Examples on the Web Most internet users will have done some form of data labeling: identifying images of traffic lights and buses for online captchas. Niamh Rowe, WIRED, 16 Oct. 2023 Bing Chat has recently been seen on Twitter solving CAPTCHA tests designed to screen out bots, which may also delay the wider release of Bing's image-processing features. Benj Edwards, Ars Technica, 18 July 2023 While some architectures can successfully navigate the human factor—such as the proof of work consensus, which was originally designed as a captcha mechanism in the early 2000s—there are multiple architectures that are more susceptible to external attacks. Dmitry Mishunin, Forbes, 28 Nov. 2023 The idea is to attach a cryptographic tag to a piece of content that verifies it was created by a human, as determined by its process of creation—a sort of captcha for digital files. Christopher Beam, WIRED, 14 Sep. 2023 By 2014, Google found that an AI could solve the most complicated CAPTCHAs with 99 percent accuracy. Kate Lindsay, The Verge, 24 Feb. 2023 Elon Musk referenced another one at last month’s Viva Technology conference in Paris: CAPTCHA puzzles. Emily Dreibelbis, PCMAG, 5 July 2023 Enhanced privacy is another big win of Apple’s CAPTCHA verification system. Chris Smith, BGR, 29 Sep. 2022 In a series of 13 tweets, Agrawal laid out how Twitter attempts to keep bots off of its platform including updating its rules and systems constantly and locking millions of accounts each week that can’t pass verification challenges like a captcha or text verification. Fortune, 16 May 2022 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'captcha.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Completely Automatic Public Turing test to tell Computers and Humans Apart (with deliberate pun on capture entry 1)

First Known Use

2001, in the meaning defined above

Time Traveler
The first known use of captcha was in 2001

Dictionary Entries Near captcha

Cite this Entry

“Captcha.” Dictionary, Merriam-Webster, Accessed 22 Feb. 2024.

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