archaean
1Archaean — Ar*ch[ae] an, a. [Gr. archai^os ancient, fr. archh beginning.] Ancient; pertaining to the earliest period in geological history. [1913 Webster] …
2Archaean — 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:… …
3Archaean — (adj.) of the earliest geological age, 1872, from Gk. arkhaios ancient, from arkhe beginning (see ARCHON (Cf. archon)) …
4Archaean — [är kē′ən] adj. ARCHEAN n. [a ] any archaebacterium …
5Archaean — /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… …
6Archaean — 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… …
7Archaean — adjective see Archean …
8archaean — adjective or noun see archaea …
9Archaean — /ahr kee euhn/, adj. Geol. Archean. * * * …
10archaean — 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 …
