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n. pl. ar·chae·a (-kē-ə)
Any of various prokaryotic microorganisms of the domain Archaea, being genetically distinct from bacteria and often living in habitats with extreme environmental conditions such as high temperature or salinity. Also called archaebacterium.

[New Latin Archaeon (back-formed singular of Archaea, domain name), from Greek arkhaion, neuter singular of arkhaios, ancient (in reference to the very ancient separation of the archaea and the eubacteria in evolutionary history); see archaic.]


Plural archaea
Any of a group of microorganisms that resemble bacteria but are different from them in certain aspects of their chemical structure, such as the composition of their cell walls. Archaea usually live in extreme environments, such as very hot or salty ones. The archaea are considered a separate kingdom in some classification systems, but a division of the prokaryotes in others. Also called archaebacterium.
References in periodicals archive ?
37) In addition to bacteria, the source of methane generation in SIBO is the archaeon Methanobrevibacter smithii.
a Novel Hyperthermophilic Archaeon Capable of Oxidizing Organic Acids and Arowing Autotrophically on Hydrogen with Fe(III) Serving as the Sole Electron Acceptor.
At present, the most widely accepted theory is that mitochondria derive from a bacterium that was engulfed by an archaeon (plural = archaea), a kind of prokaryote that looks similar to a bacterium but has many molecular differences.
Konneke M, Bernhard AE, De la Torre JR, Walker CB, Waterbury JB, Stahl DA (2005) Isolation of an autotrophic ammonia-oxidizing marine archaeon.
Mre11-Rad50 Promotes Rapid Repair of DNA Damage in the Polyploid Archaeon Haloferax volcanii by Restraining Homologous Recombination.
Did Group Ii Intron Proliferation in an Endosymbiont-Bearing Archaeon Create Eukaryotes?
Pan-genome of the dominant human gut-associated archaeon, Methanobrevibecter smithii, studied in twins.
Two-dimensional IR correlation spectroscopy of mutants of the beta-glycosidase from the hyperthermophilic archaeon Sulfolobus solfatari-cus identifies the mechanism of quaternary structure stabilization and unravels the sequence of thermal unfolding events.
Identification of a novel [alpha]-galactosidase from the hypertgermophilic archaeon Sulfolobus solfataricus.
His analysis suggests that eukaryotes are the product of a fusion of a bacterium and an archaeon.
A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents.
Halobacterium NRC-1 is an extremely halphilic archaeon that contains homologs to the E.