A diesel engine is an internal combustion engine in which oil is burnt by very hot air. Diesel engines are used in buses and trucks, and in some trains and cars. n. An internal-combustion engine that uses the heat of highly compressed air to ignite a spray of fuel introduced after the start of the compression stroke. Internal-combustion engine in which air is compressed to a temperature sufficiently high to ignite fuel injected into the cylinder, where combustion and expansion activate a piston (see piston and cylinder). It converts the chemical energy stored in the fuel into mechanical energy, which can be used to power large trucks, locomotives, ships, small electric-power generators, and some automobiles. The diesel engine differs from other internal-combustion engines (such as gasoline engines) in that it has no ignition system and so is often called a compression-ignition engine. Diesel fuel is low-grade and comparatively unrefined. Compared to other internal-combustion engines, diesel engines are more reliable, last longer, and cost less to operate, but they also produce more air pollution, noise, and vibration
(Otomotiv) An engine that burns diesel fuel instead of gasoline. The diesel oil is injected directly into the combustion chamber, where it's ignited by the heat caused by intense compression, rather than by a spark from a spark plug
A type of internal- combustion engine in which the air drawn in by the suction stroke is so highly compressed that the heat generated ignites the fuel (usually crude oil), the fuel being automatically sprayed into the cylinder under pressure