%bacterium%

‖n.; pl. Coccobacteria [ NL., fr. Gr. &unr_; a grain + NL. bacterium. So called from its round shape. ] (Biol.) One of the round variety of bacteria, a vegetable organism, generally less than a thousandth of a millimeter in diameter. [ 1913 Webster ]

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 ]

pl. [ from the pigment phycocyanin. ] any of a group of photosynthetic autotrophic prokaryotic microorganisms possessing characteristics of both bacteria and plants. When classed as bacteria, they are assigned to the Cyanobacteria; when classed as plants, they are assigned to the Cyanophyta. They were earlier named blue-green algae, a term less used now in technical discussions. Since the chlorophyll within the cyanobacteria is diffused throughout the cell, rather than being contained in chloroplasts, they are no longer thought of as true plants. [ PJC ]

n. one of the enterobacteria; a member of the family Enterobacteriaceae.
Syn. -- enteric bacterium, enteric. [ PJC ]

n.; pl. halobacteria or halobacters Any halophilic bacterium of the archaebacteria group, expecially of the genera Halobacterium and Halococcus, which live in saline environments such as the Dead Sea or salt flats.
Syn. -- halobacteria, halobacter. [ WordNet 1.5 +PJC ]

n.; pl. mycobacteria Any of various rod-shaped bacteria, some saprophytic or causing diseases. [ WordNet 1.5 ]

n.; pl. myxobacteria A type of bacteria that form colonies in self-produced slime; they inhabit moist soils or decaying plant matter or animal waste.
Syn. -- myxobacterium, myxobacter, gliding bacteria, slime bacteria. [ WordNet 1.5 ]