2 : an individual piece or a complete assembly of individual pieces, including industrial products that are manufactured as independent units, capable of being joined with other pieces or components.
The typical components referred to by the specification are valves, fittings, regulators, gauges, instrument sensors, a single length of tubing, several pieces of tubing welded together, tubing welded to fittings, and the like. [SEMI F1-90]
3 : the fundamental parts of an object, its entities, or relationships. [SEMATECH]
4 : the hardware and software that work in sets (functional entities) to perform the operation(s). [SEMATECH]