captcha

noun

capt·​cha ˈkap-chə 

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

These sites are used by hackers to present you with what appears to be a legitimate CAPTCHA verification page. —Kurt Knutsson, Cyberguy Report, Fox News, 18 Dec. 2024

Hackers are getting creative, using fake CAPTCHA buttons to sneak PowerShell commands onto your system and run malware that can steal your data. —Kurt Knutsson, Cyberguy Report, Fox News, 14 Oct. 2024

Enlarge / Examples of the kind of CAPTCHAs that image-recognition bots can now get past 100 percent of the time. —Kyle Orland, Ars Technica, 27 Sep. 2024

Brace yourself for a whole new kind of CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart). —Jill Lepore, The New Yorker, 30 Sep. 2024

Word History

Etymology

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