[ ahr-kee-uh ]
/ ˈɑr ki ə /
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plural noun, singular ar·chae·on [ahr-kee-on]. /ˈɑr kiˌɒn/. Microbiology.
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 bacteria and algae and classified as constituting the domain Archaea.
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The rainy weather could not ________ my elated spirits on my graduation day.
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See also domain (def. 6).

Origin of archaea

First recorded in 1985–90; from New Latin, from Greek archaîa, neuter plural of archaîos “ancient”; see origin at archaeo-

Other definitions for archaea (2 of 2)

[ ahr-kee-uh ]
/ ˈɑr ki ə /

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

Origin of Archaea

First recorded in 1990–95; from New Latin; see origin at archaea
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022