plural noun, singular ar·chae·bac·te·ri·um [ahr-kee-bak-teer-ee-uh m] /ˌɑr ki bækˈtɪər i əm/.
  1. a group of microorganisms, including the methanogens and certain halophiles and thermoacidophiles, that have RNA sequences, coenzymes, and a cell wall composition that are different from all other organisms: considered to be an ancient form of life that evolved separately from the bacteria and blue-green algae and sometimes classified as a kingdom.
Also ar·chae·o·bac·te·ri·a [ahr-kee-oh-bak-teer-ee-uh] /ˌɑr ki oʊ bækˈtɪər i ə/.

Origin of archaebacteria

1977; < New Latin, equivalent to archae-, irregular for archaeo- archaeo- (perhaps an erroneous Latinizing of Greek arche- arche-) + bacteria bacteria Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for archaebacteria


pl n
  1. (formerly) a group of microorganisms now regarded as members of the ArchaeaSee archaean

Word Origin for archaebacteria

from archaeo- + bacteria
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

Word Origin and History for archaebacteria

plural of archaebacterium (1977), from archaeo- + bacterium (see bacteria).

Online Etymology Dictionary, © 2010 Douglas Harper

archaebacteria in Science


Plural archaebacteria
  1. A former name for archaeon.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.