us·er·name (yōō'zər-nām') n. A sequence of characters, different from a password, that is used as identification and is required when logging on to a multiuser computer system, LAN, bulletin board system, or online service. Also called user ID.
the unique set of characters identifying a user of a shared computer program, system, or network, which allows access when coupled with a password; also written user name, also called user ID