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Archaean

adjective

  1. geological eon describing 4 to 2.5 billion years ago on Earth
L749464 on Wikidata ↗

Wiktionary

Pronunciation: /ɑːˈkiːən/ / /ɑɹˈkiːən/

adj

Etymology: From Ancient Greek ἀρχαῖα (arkhaîa, “ancient”), neuter plural of ἀρχαῖος (arkhaîos, “ancient”).

  1. Of or relating to Arche, the Muse of beginnings in Greek mythology.
  2. Of, or relating to the geologic eon from about 4,031 to 2,500 million years ago; comprises the Eoarchean, Paleoarchean, Mesoarchean and Neoarchean eras; marked by an atmosphere with little oxygen, the formation of the first continents and oceans and the emergence of simple life.

    The oldest vestiges of continental crust, which date from the Archaean aeon about 4 billion years ago, are in Acasta in north-west Canada.

  3. Of or relating to the irregular Jovian moon named for Arche.

name

Etymology: From Ancient Greek ἀρχαῖα (arkhaîa, “ancient”), neuter plural of ἀρχαῖος (arkhaîos, “ancient”).

  1. The eon from 2,500 Ma to 4,000 Ma.

noun

Etymology: Archaea + -n

  1. Any organism of the domain Archaea.