rocket engine

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

• noun A reaction engine that contains all the substances necessary for its operation and is not dependent on substances such as atmospheric oxygen, drawn from the surrounding medium, and thus is capable of operating in outer space.

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

• noun A reaction engine that obtains thrust by jet propulsion which forms its jet exclusively from propellant.

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

• noun a jet engine containing its own propellant and driven by reaction propulsion