Engine Parts Warehouse has a large selection of domestic and import remanufactured engines for your vehicle in-stock! An engine is something that produces an effect from a given input. The origin of engineering was the working of engines. There is an overlap in English between two meanings of the word "engineer": "those who operate engines" and "those who design and construct new items."

engine was any sort of mechanical device. The term "gin" in cotton gin is a short form of this usage. Practically every device from the industrial revolution was referred to as an engine, and this is where the steam engine gained its name. This form of the term has come into use again in computer science, where terms like "search engine", "3-D graphics game engine", "rendering engine" and "text-to-speech engine" are common. The earliest mechanical computing device was called the difference engine; Military devices such as catapults are referred to as siege engines.

In more recent usage, the term is used to describe devices that perform mechanical work, follow-ons to the original steam engine. In most cases the work is supplied by exerting a torque, which is used to operate other machinery, generate electricity, pump water or compress gas.

In the context of propulsion systems, an air breathing engine is one that uses atmospheric air to oxidise the fuel carried, rather than carrying an oxidiser, as in a rocket. Theoretically, this should result in a better specific impulse than for rocket engines.