/ Dictionary / Index S steam jacket: Meaning and Definition of Find definitions for: steam' jack"et Pronunciation: [key] a casing, as on the cylinder of a steam engine, filled with live steam to keep the interior hot. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. steam iron steam locomotive Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language