me·tro·ni·da·zole (m?t?r?-n??d?-z?l?)n. A synthetic antimicrobial drug, C6H9N3O3, used to treat vaginal trichomoniasis, anaerobic bacterial infections, and intestinal amebiasis.[me(thyl) + -tron- (alteration of nitro-) + (im)idazole.]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.metronidazole (?m?tr??na?d??z??l) n (Pharmacology) a pale yellow crystalline compound used to treat vaginal trichomoniasis. Formula: C6H9N3O3[C20: from me(thyl) + (ni)tro- + -n- + (im)id(e) + azole]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014