archaea

¹ American  

[ahr-kee-uh] / ˈɑr ki ə /

plural noun

Microbiology.

singular

archaeon

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 bacteria and algae and classified as constituting the domain Archaea.

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Archaea ² American  

[ahr-kee-uh] / ˈɑr ki ə /

noun

(used with a singular or plural verb)

1. (in the three-domain system of classification) the taxonomic domain comprising the archaea.

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Etymology

Origin of archaea¹

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

Origin of Archaea²

First recorded in 1990–95; from New Latin; see origin at archaea ( def. )

Example Sentences

"These Asgard archaea are often missed by low-coverage sequencing," said co-author Kathryn Appler, a postdoctoral researcher at the Institut Pasteur in Paris, France.

From Science Daily • Feb. 20, 2026

Earlier studies tested the idea that perhaps the carbon-fixing archaea were far more efficient than scientists assumed, needing less nitrogen to fix the same amount of carbon.

From Science Daily • Dec. 10, 2025

"Diverse bacteria and archaea possess the genetic capacity for MISO," explains lead author Song-Can Chen, "and they are found in a wide range of natural and human-made environments."

From Science Daily • Nov. 9, 2025

So far, it was thought that these parasitic archaea just eat any kind of lipids from their host to construct their membrane.

From Science Daily • May 1, 2024

Their study, published in Nature Communications, shows that these archaea are very 'picky eaters', which might drive their hosts to change the menu.

From Science Daily • May 1, 2024