Diesel engine definition
An internal combustion engine that uses diesel oil for fuel. The true diesel does not use a carburetor or an ignition system (i.e., spark plugs ) but injects diesel oil into the cylinders when the piston has compressed the air so tightly that it is hot enough to ignite the diesel fuel without a spark . Because a cold engine cannot ignite the diesel fuel, glow plugs are used to heat the mixture, but they do not provide a spark. Named after Rudolf Diesel, the inventor. Also see compression ignition .