ENGINE, a mechanical tool or contrivance. In the 19th cen tury the term came to have, when employed alone, a specific reference to the steam engine, but it is also used of other prime movers such as the internal combustion engine. For accounts of the various types of engines see: STEAM ENGINE; INTERNAL COM BUSTION ENGINES ; DIESEL ENGINE ; TURBINE, STEAM ; TURBINE, WATER; MARINE ENGINEERING; LOCOMOTIVE; REFRIGERATION; AIR-ENGINE ; FIRE ENGINE.