From The Free On-line Dictionary of Computing: (http://www.foldoc.org/, Editor Denis Howe)
The person who uses a computer application, as opposed to those who developed or support it. The end-user may or may not know anything about computers, how they work, or what to do if something goes wrong. End-users do not usually have administrative responsibilities or privileges.
End users are certain to have a different set of assumptions than the developers who created the application.