Definition from Wiktionary, the free dictionary
Archaean (not comparable)
- (geology) 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 continents and oceans and the emergence of simple life
of eon from 3,800 to 2,500 million years ago
- (geology) The eon from 2,500 Ma to 4,000 Ma.
- (eon 2,500-4,000 Ma): Precambrian