/ Dictionary / Index A air jacket: Meaning and Definition of Find definitions for: air' jack"et Pronunciation: [key] an envelope of enclosed air around part of a machine, as for checking the transmission of heat. See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. airish air kiss Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language