Any of the unicellular prokaryotic microorganisms of the class Schizomycetes, which vary in terms of morphology, oxygen and nutritional requirements, and motility, and may be free-living, saprophytic, or pathogenic in plants or animals.
Origin:
Origin: New Latin bactērium
Origin: , from Greek baktērion
Origin: , diminutive of baktron, rod; see bak- in Indo-European roots