A diesel is a type of engine that produces enough heat to burn fuel and power a vehicle. Most diesels run on very thick, heavy oil.

Large trucks use diesels — also known as diesel engines — and so do some cars, trains, and ships. The earliest diesel was developed in the late 19th century, and its invention is credited to the German engineer Rudolph Diesel, although other inventors laid the groundwork with their development of a very similar type of engine.

Definitions of diesel
  1. noun
    an internal-combustion engine that burns heavy oil
    synonyms: diesel engine, diesel motor
    see moresee less
    type of:
    ICE, internal-combustion engine
    a heat engine in which combustion occurs inside the engine rather than in a separate furnace; heat expands a gas that either moves a piston or turns a gas turbine
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