plas·min·o·gen (pl?z-m?n??-j?n)n. The inactive precursor to plasmin that is found in body fluids and blood plasma.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.plasminogen (plæz?m?n?d??n) n (Biochemistry) biochem a zymogen found in blood that gives rise to plasmin on activationCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014plas?min?o?gen (plæz?m?n ? d??n, -?d??n) n. a substance in the blood that forms plasmin when activated. [1940?45] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.