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n. pl. mare's-tails or mares'-tails (mârz′tālz′)
1. A cosmopolitan aquatic herb (Hippuris vulgaris) having inconspicuous flowers and linear whorled leaves on erect unbranched stems.
2. See horseweed.
3. A long narrow cirrus cloud with a flowing appearance.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
1. (Physical Geography) a wisp of trailing cirrus cloud, often indicating high winds in the upper troposphere
2. (Plants) an erect cosmopolitan pond plant, Hippuris vulgaris, with minute flowers and crowded whorls of narrow leaves: family Hippuridaceae
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
1. a long narrow cirrus cloud with a flowing appearance.
2. an erect aquatic Old World plant, Hippuris vulgaris, of the family Hippuridaceae, with crowded whorls of narrow hairlike leaves.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.