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

Humans are better than computers at deciphering letters and words; early CAPTCHAs displayed an image of distorted text, which the viewer had to type correctly to proceed. —Alan Burdick, New York Times, 16 May 2025

Companies are also implementing additional measures such as CAPTCHAs, IP blocks and advanced anti-bot technology. —Rochelle Thielen, Forbes.com, 21 May 2025

This is not normal behavior, and there’s no reason on earth why a captcha verification should ask you to do such a thing. —Davey Winder, Forbes.com, 5 May 2025

The hack placed a fake CAPTCHA test on the landing page for iClicker.com, according to BleepingComputer. —Michael Kan, PC Magazine, 12 May 2025

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