1. (Or "uid", "user id") A number or nAMe which is unique to a particular user of a computer or group of computers which share user information. The {operating system} uses the uid to represent the user in its data structures, e.g. the owner of a file or process, the person attempting to access a system resource etc. A user database, e.g. Unix' s /etc/passwd file or NIS, maps the uid to other information about that user such as their user nAMe, password, home directory and real nAMe. 2. user nAMe. (1997-03-01)