Definition of "archaeon" []

• Any of various single-celled prokaryotes genetically distinct from bacteria, often thriving in extreme environmental conditions. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Jarrell 2007 Systematic deletion analyses of the fla genes in the flagella operon identify several genes essential for proper assembly and function of flagella in the archaeon, Methanococcus maripaludis."
• "I seem to remember that you have previously been very critical of the traditional endosymbiotic hypothesis for the origin of the nucleus (where the nucleus arose from an archaeon engulfed by a bacterium)."
• "What's interesting about this study is that it challenges a widely held hypothesis that Eucarya arose out of the fusion of a bacterium with an archaeon (also known as the endosymbiotic origin of the nucleus, not to be confused with the endosymbiotic origin of mitochondria and chloroplasts)."