/ Dictionary / Index M mare clausum: Meaning and Definition of Find definitions for: ma•re clau•sum Pronunciation: (mâr'ē klô'sum, mär'ā Lat. mä're klou's&oobrevem), [key] a body of navigable water under the sole jurisdiction of a nation. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Mare Cimmerium Mare Crisium Related Content Daily Word Quiz: exemplary Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language