co·ry·ne·bac·te·ri·um (kôr??-n?-b?k-tîr??-?m, k?-r?n??-)n. pl. co·ry·ne·bac·te·ri·a (-tîr??-?) Any of various gram-positive, rod-shaped bacteria of the genus Corynebacterium, which includes many animal and plant pathogens, such as the causative agent of diphtheria.[New Latin Coryn?bacterium, genus name : Greek korun?, club; see ker- in Indo-European roots + bacterium.]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.corynebacterium (?k?r?n?bæk?t??r??m) n, pl corynebacteriaany of various bacterium of the genus Corynebacterium, including various animal and plant pathogens and animal parasitesCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014