A program (and by implication usually the computer it runs in) that "serves" the resources (files, storage, application programs, printers, and other devices) for a number of attached workstations.
A data station that provides specific services to other data stations on a local area network. For example, a file server, print server, mail server.
A general term used to describe a device that manages and allows the use of more than one kind of resource, such as storage or file services, print services, communication services, data base services, etc.