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

The internet is full of accounts of the difficulties of captchas for the visually impaired, so ChatGPT’s training data is full of them, too. —Amanda Gefter, Quanta Magazine, 10 Apr. 2026

Billboard and many streaming platforms now use AI algorithms and captchas to detect abnormal play patterns. —Kyle Eustice, VIBE.com, 30 Mar. 2026

Typically, these types of bait come in the form of fake CAPTCHAs that—rather requiring users to click a box or identify objects or letters in a jumbled image—instruct them to copy text and paste it into an interface, a process that takes just seconds. —Dan Goodin, ArsTechnica, 11 Feb. 2026

Hackers have previously dressed up the attack method as online CAPTCHA screens or security alerts from Chrome or Facebook. —PC Magazine, 25 Nov. 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