User (noun)

1. A person who uses something.
2. A person who uses a particular service or system.
3. A person who operates a machine or computer.

Origin:

Late middle english: from old french, from latin usarius "useful", from uti "to use".

Examples:

1. The software is designed for both professional and home users.
2. The website has a large number of daily users.
3. The phone has a user-friendly interface.
4. The machine has a user manual.
5. The system has a user login feature.