an·ti·his·ta·mine (?n?t?-h?s?t?-m?n?, -m?n, ?n?t?-) n. Any of various drugs used to counteract the physiological effects of histamine production in allergic reactions and colds. an?ti·his?ta·min?ic (-m?n??k) 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.antihistamine (?ænt??h?st??mi?n; -m?n) n (Pharmacology) any drug that neutralizes the effects of histamine, used esp in the treatment of allergiesCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014an?ti?his?ta?mine (?æn ti?h?s t??min, -m?n, ?æn ta?-) n. any of various synthetic compounds capable of blocking the action of histamines, used esp. for treating allergies and gastric ulcers. [1930?35] an`ti?his`ta?min?ic (-?m?n ?k) adj. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.an·ti·his·ta·mine (?n?t?-h?s?t?-m?n?) Any of various drugs that relieve cold or allergy symptoms by blocking the action of histamine in the body.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.