Real Dictionary

bacteria in American English
any of a division (Bacteria) of monerans, microorganisms which are typically one-celled, have no chlorophyll, multiply by simple division, and can be seen only with a microscope: they occur in three main forms, spherical (cocci), rod-shaped (bacilli), and
plural noun: 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 i

bacteria in British English
plural noun: 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