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

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

Older text-identification CAPTCHAs have long been solvable by AI models. —Benj Edwards, Ars Technica, 27 Sep. 2024

But in reality, the fake CAPTCHA test is designed to manipulate users into installing the password-looting Lumma Stealer malware. —Michael Kan, PCMAG, 23 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