Definition of captcha in English:


(also captcha)


  • A program or system intended to distinguish human from machine input, typically as a way of thwarting spam and automated extraction of data from websites.

    • ‘Those familiar squiggly letters are Captchas, an upgraded security measure used by many Web sites to distinguish humans from spambots.’
    • ‘Anecdotal evidence also suggests that CAPTCHAs are getting harder, with some effectively indecipherable.’
    • ‘The captcha is the junk filter's last resort.’
    • ‘The spammers are thinking up ever more ingenious ways to break the captchas.’
    • ‘And despite the fact that Captchas are unpopular with some people, their use is increasing.’
    • ‘The website employs captchas, where you guess, then type, the correct series of letters into a textbox for authentication purposes.’
    • ‘You could always add a CAPTCHA to the comments submission system.’
    • ‘Most Captcha programs apply mathematical transformations to their images which can potentially be reversed, thus allowing spammers to crack the Captcha.’
    • ‘Keep in mind, Captchas can most likely easily keep ahead of the state of AI for many years to come.’
    • ‘But resourceful hackers have found ways to solve Captchas, and he has had to rethink the program.’
    • ‘The goal of CAPTCHAs is to authenticate that there's a person sitting in front of the computer.’
    • ‘I guess the spammers tools are too simplistic to even attempt to break the captcha.’
    • ‘Every time you edit a page, you have to pass a captcha.’
    • ‘The point of the CAPTCHA is that reading those swirly letters is something that computers aren't very good at.’
    • ‘"Within five years, about 200 million Captchas were being typed everyday," he says.’
    • ‘As captchas have become more sophisticated, in an arms race against algorithms designed to crack them, humans often make errors reading them.’
    • ‘An estimated 6 million Captchas are completed each day, costing users 10 seconds each, wasting an overwhelming number of labor hours.’
    • ‘I can "solve" most CAPTCHAs in a few seconds.’
    • ‘The whole point of CAPTCHAs is to ensure that it's a real person visiting a website, not just a bot on a computer.’
    • ‘Their technology provides overrides for false hits on open proxies via CAPTCHA.’


Early 21st century: acronym from completely automated public Turing test to tell computers and humans apart.