Breadcrumb Home > Dictionary > Index R reaction engine: Meaning and Definition of Find definitions for: reac'tion en"gine Pronunciation: [key] — Aeron., Rocketry. Aeron.,Rocketry. an engine that produces power as a reaction to the momentum given to gases ejected from it, as a rocket or jet engine. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. reactionary reaction formation TrendingHere are the facts and trivia that people are buzzing about. Jewish Holidays, 2010-2030 (A.M. 5770-5791) Western Christian Holidays, 2010-2030 12 Steps to a New Year New Year's Resolution to Slim Down? Martin Luther King Speeches Books of the Bible: Old Testament Books in Order ✖ Related Content Daily Word Quiz: fatuous Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language