/ Dictionary / Index E Express Mail: Meaning and Definition of Find definitions for: Express' Mail" Pronunciation: [key] — Trademark. Trademark. an expedited domestic mailing service of the U.S. Postal Service, usually guaranteeing delivery overnight or within 24 hours. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. expressly expressman Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language