Breadcrumb Home > Dictionary > Index U union card: Meaning and Definition of Find definitions for: un'ion card" Pronunciation: [key] a card identifying one as a member of a particular labor union. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. union buster union catalog ✖ Related Content Daily Word Quiz: hortatory Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language