/ Dictionary / Index M main deck: Meaning and Definition of Find definitions for: main' deck' Pronunciation: [key] the uppermost weatherproof deck, running the full length of a ship. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. main course main-de-fer Related Content Daily Word Quiz: philtrum Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language