corynebacterium \co`ry*ne`bac*ter"i*um\, n. (MIcrobiol.) Any member of the genus {Corynebacterium}, consisting of gram-positive usually nonmotile irregularly rod-shaped bacteria, some of which are pathogenic or parasitic in humans and domestic animals, such as {Corynebacterium diphtheriae}, which causes diphtheria. [PJC]