os·to·my (?s?t?-m?)n. pl. os·to·mies Surgical construction of an artificial excretory opening, as a colostomy or ileostomy.[From (col)ostomy.]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.ostomy (??st?m?) npl -miespl -mies1. (Medicine) a surgically created opening2. (Medicine) the surgery that creates such an openingCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014os?to?my (??s t? mi) n., pl. -mies. any of various surgical procedures in which an artificial opening is made for the drainage of waste products. [1955?60; generalized from words in which -ostomy is the final element; see -o-, -stomy] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.