Definition of archaebacteria in English:


Pronunciation /ˌärkēbakˈtirēə/ /ˌɑrkibækˈtɪriə/

plural nounarchaebacterium

  • Microorganisms that are similar to bacteria in size and simplicity of structure but radically different in molecular organization. They are now believed to constitute an ancient intermediate group between the bacteria and eukaryotes.

    Also called archaea

    ‘What's more, these origin-of-life researchers suspect that the two major groups of bacteria, known as archaebacteria and eubacteria, originated on two separate occasions about 3.8 billion years ago.’
    • ‘The most startling (and, for some people, unbelievable) such event was the origin of the eukaryotes by the fusion of an archaebacterium with some eubacteria.’
    • ‘They conjecture that an evolutionary quantum leap happened after an archaebacterium swallowed a eubacterium.’
    • ‘These sequences included proteins from a diverse range of organisms, ranging from eubacteria and archaebacteria to algae, fungi, and plants.’
    • ‘These ‘bugs, ‘actually archaebacteria, thrive in intense heat and pressure deep underground, without any light - that is, in a truly alien environment within planet earth.’’


1970s modern Latin (plural), from Greek arkhaios ‘primitive’.