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• archaea
  archaea

  plural noun

  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.
• Archaea
  Archaea

  noun

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

archaea

¹ American  

[ahr-kee-uh] / ˈɑr ki ə /

plural noun

Microbiology.

archaeon singular

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

See Examples For:

archaea Archaea archaeon

Baker's team studies the genomes of Asgard archaea to identify new branches of the group and better understand how these microbes generate energy.

From Science Daily ● Feb. 20, 2026

Writing in the journal Nature, the team focused on a group of microbes called Asgard archaea, which are considered close relatives of the ancestors of complex life.

From Science Daily ● Feb. 20, 2026

The pool of likely contributors now includes additional types of microbes in the surrounding community, particularly bacteria and some archaea.

From Science Daily ● Dec. 10, 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

In the new study, Nayak and former graduate student Katie Shalvarjian surveyed a wide range of Archaea and found that many lineages produce pyrrolysine.

From Science Daily ● Feb. 28, 2026

The organism is a methane producing member of a group of microbes known as Archaea.

From Science Daily ● Feb. 28, 2026

"Archaea are often called ancient bacteria," says Spang.

From Science Daily ● Nov. 21, 2023

The earth’s history is divided into four eons, the Pre-Archean, Archaea, Proteozoic, Phanerozoic.

From Textbooks ● Jan. 1, 2015

The groups within Archaea and Eukarya are then connected together.

From Textbooks ● Jan. 1, 2015

The prevailing model holds that eukaryotes arose when an Asgard archaeon formed a symbiotic relationship with an alphaproteobacterium.

From Science Daily ● Feb. 20, 2026

In every place, copies of the Borg co-occurred with DNA linked to a methane-oxidizing archaeon called Methanoperedens.

From Science Magazine ● Jul. 15, 2021

He is part of a team that spent a decade trying to determine the physical shape of a particular protein in a tiny bacteria-like organism called an archaeon.

From New York Times ● Nov. 30, 2020

In the end, they found 17 enzymes from 9 different organisms, including E. coli, an archaeon, the plant Arabidopsis and humans.

From Nature ● Nov. 6, 2018

The first option, called the big-bang or mitochondria-early theory, predicts that a primitive archaeon engulfed a bacterium, an event that drove the development of eukaryotes.

From Scientific American ● Nov. 30, 2015