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

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

Operator can’t currently log into websites on your behalf, solve CAPTCHAs, or enter credit card information. —Adam Clark Estes, Vox, 7 Dec. 2018

New tools, going beyond CAPTCHAs, will be developed to tackle increasingly sophisticated bots. —Sarwant Singh, Forbes, 22 Jan. 2025

The breach underscores the importance of implementing defenses like CAPTCHA and other automated bot detection tools in systems handling sensitive data. —Lars Daniel, Forbes, 26 Nov. 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