'archean' definitions:
Definition of 'archean'
(from WordNet)
adjective
Of or relating to the earliest known rocks formed during the Precambrian Eon [syn: archean, archaean]
noun
The time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life [syn: Archean, Archean eon, Archean aeon, Archeozoic, Archaeozoic, Archeozoic eon, Archaeozoic aeon]