Archean aeon
n 1: 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}]