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English definition of “bacterium”


noun [C usually plural]     /bækˈtɪə.ri.əm/ US  /-ˈtɪr.i-/ (plural bacteria)
C1 a type of very small organism that lives in air , earth , water , plants , and animals , often one that causes disease : an illness caused by bacteria in drinking water The bacterium Streptococcus pneumoniae causes about a third of some 3,000 annual meningitis cases .Bacteria, moulds, germs and viruses
(Definition of bacterium noun from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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