/ Dictionary / Index A air mass: Meaning and Definition of Find definitions for: air' mass" Pronunciation: [key] a body of air covering a relatively wide area, exhibiting approximately uniform properties through any horizontal section. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. air marshal air mattress Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language