tro·pine (tr??p?n?, -p?n) also tro·pin (-p?n)n. A white, crystalline, poisonous alkaloid, C8H15NO, obtained chiefly by hydrolysis of atropine.[From atropine.]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.tropin (?tr??p?n) na hormone released in the body by a certain gland and which produces a response in other glands, stimulating the release of other hormonesCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014