Archaean
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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 — 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:… … 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 — 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
