404
Americannoun
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Also called 404 error. Computers. an error message sent by a web server to a browser when the user has typed an incorrect URL, tried to access a web page that is no longer available, or clicked on a broken link on a web page.
They must have taken down their website;
I keep getting that annoying “404 - File Not Found” message.
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Slang. a person who is stupid or uninformed.
noun
Etymology
Origin of 404
First recorded in 1995–2000
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Only around a third of Angus’s 404 owners have plied their tokenized shares of the animal into the artists’ online Remorse Portal, signifying their wish to save his life.
From The Wall Street Journal • Mar. 11, 2026
The company’s data-sharing with federal authorities and cybersecurity lapses have been documented by 404 Media and other outlets.
From Los Angeles Times • Mar. 1, 2026
Emails from company founder Jamie Siminoff shared by 404 Media show that the company had no intention of stopping with dogs and cats.
From Salon • Feb. 18, 2026
The BBC has asked 280 Labour MPs of the 404 currently sitting in Parliament what their views were on Burnham attempting to become an MP again.
From BBC • Jan. 23, 2026
Olanna watched the Peugeot 404 disappear down the road and stood there for a while, feeling as if she had swallowed a sparkling sliver of light.
From "Half of a Yellow Sun" by Chimamanda Ngozi Adichie
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.