404. noun

Definitions

1. (computing, web) An error code that means the webpage or resource you were trying to reach could not be found on the server.

• Example 1: When I clicked the link, I got a 404 instead of the page I expected.

• Example 2: A 404 shows up if you type the wrong website address.

2. (informal, slang) A person who seems lost, confused, or unable to understand something, based on the 404 error message meaning "not found."

• Example 1: When I asked him about the problem, he was a total 404.

• Example 2: In the meeting, she looked like a 404 during the technical discussion.

Etymology

The term "404" comes from the HTTP status code system in web servers. In this system, different numbers mean different responses. "404" was chosen to mean "not found" by the creators of the HTTP protocol in the early days of the World Wide Web. It was first used by web browsers when a requested page could not be found.