Archaean Ar*ch[ae]"an, n. (Geol.) The earliest period in geological period, extending up to the Lower Silurian. It includes an Azoic age, previous to the appearance of life, and an Eozoic age, including the earliest forms of life. [1913 Webster]

Note: This is equivalent to the formerly accepted term Azoic, and to the Eozoic of Dawson. [1913 Webster]

The Collaborative International Dictionary of English. 2000.

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  • Archaean — Ar*ch[ae] an, a. [Gr. archai^os ancient, fr. archh beginning.] Ancient; pertaining to the earliest period in geological history. [1913 Webster] …   The Collaborative International Dictionary of English

  • Archaean — (adj.) of the earliest geological age, 1872, from Gk. arkhaios ancient, from arkhe beginning (see ARCHON (Cf. archon)) …   Etymology dictionary

  • Archaean — [är kē′ən] adj. ARCHEAN n. [a ] any archaebacterium …   English World dictionary

  • Archaean — /aˈkiən/ (say ah keeuhn) Geology –noun 1. the aeon extending from 3800–2500 million years ago or the series of predominantly igneous and metamorphic rocks formed then. 2. Obsolete the span of geological time before the Proterozoic, including the… …  

  • Archaean — 1. adjective of, or relating to the geologic eon from about 3,800 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… …   Wiktionary

  • Archaean — adjective see Archean …   New Collegiate Dictionary

  • archaean — adjective or noun see archaea …   New Collegiate Dictionary

  • Archaean — /ahr kee euhn/, adj. Geol. Archean. * * * …   Universalium

  • archaean — adj. (Geology) of or pertaining to the earliest known forms of rocks; of or belonging to the earlier of the two divisions of Precambrian time …   English contemporary dictionary

  • Archaean — [α: ki:ən] (US Archean) adjective Geology relating to or denoting the earlier part of the Precambrian aeon (before about 2,500 million years ago), in which there was no life on the earth. Origin C19: from Gk arkhaios ancient + an …   English new terms dictionary

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