hy·per·pla·sia (h??p?r-pl??zh?)n. An abnormal increase in the number of cells in a tissue or organ, with consequent enlargement of the part or organ.hy?per·plas?tic (-pl?s?t?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.hyperplasia (?ha?p??plæz??) n (Pathology) enlargement of a bodily organ or part resulting from an increase in the total number of cells. Compare hypertrophy hyperplastic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014hy?per?pla?sia (?ha? p?r?ple? ??, -?i ?, -zi ?) n. 1. abnormal multiplication of cells. 2. enlargement of a part due to an abnormal numerical increase of its cells. [1860?65] hy`per?plas?tic (-?plæs t?k) adj. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.