1. A person, organization, or other entity (including a computer or computer system,) that employs the services provided by a telecommunication system, or by an information processing system, for transfer of information. Note: A user functions as a source or final destination of user information, or both. Synonym subscriber. 2. Person or process authorized access to an IS (information system); An individual defined, registered, and bound to a public key structure by certification authority. 3. A person who interacts with a system. 4. Any person who interacts with a computer system. 5. Any person who interacts directly with a computer system.