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

Security researchers have unmasked a campaign using both fake CAPTCHA tests and malicious downloads as the starting point for what quickly turns into an invisible rootkit attack that can cloak any malicious file, task or Windows registry entry that uses one specific prefix. —Davey Winder, Forbes, 17 Mar. 2025

Faced with one of those annoying CAPTCHA prompts on her screen, Lara clicks as directed, but keeps failing the test. —Peter Debruge, Variety, 2 Mar. 2025

For example, CAPTCHAs—long considered a staple in bot mitigation—are no match for AI models capable of solving them almost instantaneously. —Benjamin Fabre, Forbes, 3 Mar. 2025

Follow my guide to learn how to spot the signs of a fake CAPTCHA designed to download malware. —Kurt Knutsson, Cyberguy Report, Fox News, 23 Feb. 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