an·ti·co·ag·u·lant (?n?t?-k?-?g?y?-l?nt, ?n?t?-)n. A substance that slows or prevents the clotting of blood.adj. Acting as an anticoagulant.an?ti·co·ag?u·la?tive (-l??t?v, -l?-t?v) adj.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.anticoagulant (?ænt?k???æ?j?l?nt) adj (Medicine) acting to prevent or impair coagulation, esp of bloodn (Pharmacology) an agent that prevents or impairs coagulationCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014an?ti?co?ag?u?lant (?æn ti ko??æg y? l?nt, ?æn ta?-) adj. 1. Also, an?ti?co?ag?u?la?tive (-?le? t?v, -l? t?v) preventing coagulation, esp. of blood. n. 2. an anticoagulant agent, as heparin. [1900?05] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.anticoagulantA drug used to decrease the clotting ability of the blood, especially after heart surgery.Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited