/ Dictionary / Index Z ZIP + 4: Meaning and Definition of Find definitions for: ZIP + 4 Pronunciation: (zip' plus" fôr', fōr'), [key] a zip code of nine digits, used to facilitate accurate and prompt delivery of mail. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. zippered Zipporah 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