/ Dictionary / Index M mag card: Meaning and Definition of Find definitions for: mag' card" Pronunciation: (mag), [key] a plastic or paper card with a magnetizable layer on which data can be recorded and from which data can be read. such a card used in access-control systems, as for automatically unlocking doors. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. magazinist Magda Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language