internal-combustion engine

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An engine, such as an automotive gasoline piston engine or a diesel, in which fuel is burned within the engine proper rather than in an external furnace, as in a steam engine.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Alternative form of internal combustion engine.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun 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