/ Dictionary / Index M margin plank: Meaning and Definition of Find definitions for: mar'gin plank" Pronunciation: [key] a plank forming a border for wooden decking. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. margin of safety margosa Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language