[ bak-teer-ee-uh ]
/ bækˈtɪər i ə /
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plural noun, singular bac·te·ri·um [bak-teer-ee-uhm]. /bækˈtɪər i əm/. Microbiology.
ubiquitous one-celled organisms, spherical, spiral, or rod-shaped and appearing singly or in chains, comprising numerous and variously classified phyla: among the inestimable number of species are those involved in fermentation, putrefaction, infectious diseases, and nitrogen fixation.
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Origin of bacteria

First recorded in 1860–65; from New Latin, from Greek baktḗria, plural of baktḗrion, diminutive of baktēría “staff, cane”; see origin at bacterium


bac·te·ri·al, adjectivebac·te·ri·al·ly, adverbnon·bac·te·ri·al, adjectivenon·bac·te·ri·al·ly, adverb

Other definitions for bacteria (2 of 2)

[ bak-teer-ee-uh ]
/ bækˈtɪər i ə /

noun (used with a singular or plural verb)Microbiology.
(in the three-domain system of classification) the taxonomic domain comprising the bacteria.
See also domain (def. 6).

Origin of Bacteria

First recorded in 1860–65; from New Latin; see origin at bacteria
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use bacteria in a sentence

British Dictionary definitions for bacteria

/ (bækˈtɪərɪə) /

pl n singular -rium (-rɪəm)
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 animalsSee also prokaryote

Derived forms of bacteria

bacterial, adjectivebacterially, adverb

Word Origin for bacteria

C19: plural of New Latin bacterium, from Greek baktērion, literally: a little stick, from baktron rod, staff
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for bacteria

[ băk-tîrē-ə ]

Plural of bacterium.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for bacteria


sing. bacterium

Microorganisms made up of a single cell that has no distinct nucleus. Bacteria reproduce by fission or by forming spores.

notes for bacteria

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).
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.