username
n.the unique name you use to identify yourself when you log in to a computer system or website.
n.a unique sequence of characters used to identify a specific user during the authentication process on a computer system or network.
“Please enter your username and password to log in.”
“When you create a new account, the system checks if your chosen username is already taken by another person.”
“For security reasons, the administrator recommends choosing a username that does not contain your real name or any easily identifiable personal information.”
Often paired with 'password' in the context of digital security.
A compound formed from the noun user and the noun name. It emerged in the mid-twentieth century as a functional descriptor within early multi-user computing environments.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.