username

username [yoo-zer-neym] noun Computers.

1. Also called login name, logon name, sign-in name, sign-on name. a unique sequence of characters used to identify a user and allow access to a computer system, computer network, or online account.
2. the part of an email address before the @ sign.

Also called user ID. British Dictionary definitions for user id username noun

1. computing a name that someone uses for identification purposes when logging onto a computer, using chatrooms, or as part of his or her e-mail address

Word Origin and History for user id username n.

by 1982, from user + name (n.).