four-stroke engine

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

• noun An engine in which the pistons perform four strokes per engine cycle (i.e. intake, compression, power, exhaust).

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

• noun an internal-combustion engine in which an explosive mixture is drawn into the cylinder on the first stroke and is compressed and ignited on the second stroke; work is done on the third stroke and the products of combustion are exhausted on the fourth stroke