username

[ yoo-zer-neym ]
/ ˈyu zərˌneɪm /

noun Computers.

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.
the part of an email address before the @ sign.
Also called user ID.

British Dictionary definitions for login-name

username
/ (ˈjuːzəˌneɪm) /

noun

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