- archean, archaean - used of the earliest known rocks
Antonym: middle (indirect, via late, early)
Antonym: late (indirect, via early, middle)
- Archean, Archean eon, Archean aeon, Archeozoic, Archaeozoic, Archeozoic eon, Archaeozoic aeon - the time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life
--1 is a kind of eon, aeon
--1 is a part ofPrecambrian, Precambrian eon, Precambrian aeon, Precambrian period