ubiquitous one-celled organisms, spherical, spiral, or rod-shaped and appearing singly or in chains, comprising the Schizomycota, a phylum of the kingdom Monera (in some classification systems the plant class Schizomycetes), various species of which are involved in fermentation, putrefaction, infectious diseases, or nitrogen fixation.
a very large group of microorganisms comprising one of the three domains of living organisms. They are prokaryotic, unicellular, and either free-living in soil or water or parasites of plants or animals See also prokaryote
bacterial, adjective bacterially, adverb
C19: plural of New Latin bacterium, from Greek baktērion, literally: a little stick, from baktron rod, staff
1847, from Mod.L. pl. of bacterium, from Gk. bakterion "small staff," dim. of baktron "stick, rod," from PIE *bak- "staff used for support." So called because the first ones observed were rod-shaped. Introduced as a scientific word 1838 by Ger. naturalist Christian Gottfried Ehrenberg (1795-1876). Related: Bacterial (1871).