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Having no placenta, as marsupials and monotremes.
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.
(Zoology) (of monotremes and marsupials) having no placenta
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
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|Adj.||1.||aplacental - having no placenta; "monotremes and marsupials are aplacental mammals"|
placental - pertaining to or having or occurring by means of a placenta; "all mammals except monotremes and marsupials are placental mammals"
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.