/ Dictionary / Index M macoma: Meaning and Definition of Find definitions for: ma•co•ma Pronunciation: (mu-kō'mu), [key] — n. any marine bivalve mollusk of the genus Macoma, having a glossy, thin, usually white shell. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. maco Macomb Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language