/ Dictionary / Index M mare's-tail: Meaning and Definition of Find definitions for: mare's-tail Pronunciation: (mârz'tāl"), [key] — n. a long narrow cirrus cloud whose flowing appearance somewhat resembles a horse's tail. an erect, aquatic, Old World plant, Hippuris vulgaris, having crowded whorls of narrow, hairlike leaves. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mare's-tail (Thesaurus) mares of Diomedes Mare Tranquillitatis Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language