/ Dictionary / Index M Mare Acidalium: Meaning and Definition of Find definitions for: Ma•re Ac•i•dal•i•um Pronunciation: (mär'ā as"i-dal'ē-um, mâr'ē), [key] (Sea of Venus) an area in the northern hemisphere of Mars, appearing as a dark region when viewed telescopically from the earth. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. mare Mare Australe Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language