[bak-teer-ee-uh] 
[-teer-ee-uh
m] . | 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. |
| bac·te·ri·al (bāk-tîr'ē-əl) adj. Relating to or caused by bacteria: a bacterial enzyme; bacterial diseases. bac·te'ri·al n., bac·te'ri·al·ly adv. |
sing. bacterium
Microorganisms made up of a single cell that has no distinct nucleus. Bacteria reproduce by fission or by forming spores.
Note: Some bacteria are beneficial to humans (for example, those that live in the stomach and aid digestion), and some are harmful (for example, those that cause disease).
| bacterium (bāk-tîr'ē-əm) Pronunciation Key
Plural bacteria Any of a large group of one-celled organisms that lack a cell nucleus, reproduce by fission or by forming spores, and in some cases cause disease. They are the most abundant lifeforms on Earth, and are found in all living things and in all of the Earth's environments. Bacteria usually live off other organisms. Bacteria make up most of the kingdom of prokaryotes (Monera or Prokaryota), with one group (the archaea or archaebacteria) often classified as a separate kingdom. See also archaeon, prokaryote. bacterial adjective Our Living Language : It is important to remember that bacteria is the plural of bacterium, and that saying a bacteria is incorrect. It is correct to say The soil sample contains millions of bacteria, and Tetanus is caused by a bacterium. |
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