archaea

¹

[ ahr-kee-uh ]

plural noun

, Microbiology.

, singular ar·chae·on [ahr, -kee-on].

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.

Archaea

²

[ ahr-kee-uh ]

noun

, (used with a singular or plural verb)

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

Word History and Origins

Origin of archaea¹

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

Origin of archaea²

First recorded in 1990–95; from New Latin; archaea ( def )

Example Sentences

Archaea are single-celled microorganisms that are similar to bacteria but differ in compositions.

From Nautilus