Also found in: Thesaurus, Medical, Encyclopedia.


Variant of Archean.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Biology) any member of the Archaea, a domain of prokaryotic microorganisms, distinguished from bacteria on molecular phylogenetic grounds and often found in hostile environments, such as volcanic vents and hot springs


(ɑːˈkiːən) or


(Geological Science) of or relating to the highly metamorphosed rocks formed in the early Precambrian era
(Geological Science) the earlier of two divisions of the Precambrian era, during which the earliest forms of life are assumed to have appeared
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.archaean - of or relating to the earliest known rocks formed during the Precambrian Eon
geology - a science that deals with the history of the earth as recorded in rocks
early - at or near the beginning of a period of time or course of events or before the usual or expected time; "early morning"; "an early warning"; "early diagnosis"; "an early death"; "took early retirement"; "an early spring"; "early varieties of peas and tomatoes mature before most standard varieties"
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
This Archaean greenstone belt is predominantly composed of tholeiitic basalt lava and volcaniclastic deposits, ultramafic rocks, felsic volcanic rocks and sediments surrounded by younger Archaean granitoids.
The Western Queen Gold project lies within the Warda Warra (Archaean) Greenstone Belt, a part of the Murchison Province of the Yilgarn Craton.
For their research, the team analysed a piece of rock melt, called komatiite -- named after the type occurrence in the Komati river near Barberton in Mpumalanga -- that are the leftovers from the hottest magma ever produced in the first quarter of Earth's existence (the Archaean).
The preservation of so much Archaean geology, dating back more than 2 500 million years, has resulted in the Archaean Witwatersrand Basin, as well as several greenstone belts, being preserved.
The SG-3 geological section whose pilot borehole reached 12262 m is represented by two complexes - Proterozoic and Archaean.
One species tested, an archaean called Methanothermococcus okinawensi, fared the best on faux Enceladus.
A methanogenic (methane-producing) archaean called Methanothermococcus okinawensis thrived in laboratory conditions mimicking those thought to exist on Saturn's satellite, the team said.
The study area belongs to the Pan-African belt (Figure 1), also interpreted as the result of the convergence and collision between the steady Archaean Congo Craton to the south and one or two Paleoproterozoic plates [16,17].
Micklethwaite and Cox [15, 26] pioneered this approach by applying it to the analysis of gold deposition near auriferous Archaean faults.
"Our results imply that a mantle reservoir as hot as those responsible for some Archaean lavas has survived eons of convection in the deep Earth and is still being tapped by mantle plumes," the study said.
Among her topics are sexuality and convention, Archaean schist in a volcanic world: geography from a Reachfar perspective, fro Tinker to Toff: ranking the friends, illness and disability among friends, and much beloved but soon forgotten: critical reception of Duncan's novels.