/ Dictionary / Index P post exchange: Meaning and Definition of Find definitions for: post' exchange" Pronunciation: [key] — U.S. Army. U.S. Army. a retail store on an army installation that sells goods and services to military personnel and their dependents and to certain authorized civilian personnel. Abbr.: PX Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. poster paint postexilic Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language