component

Uniquely identifiable input, part, piece, assembly or subassembly, system or subsystem, that (1) is required to complete or finish an activity, item, or job, (2) performs a distinctive and necessary function in the operation of a system, or (3) is intended to be included as a part of a finished, packaged, and labeled item. Components are usually removable in one piece and are considered indivisible for a particular purpose or use. Commonly, items of very small or insignificant cost are not considered components.