- Precambrian, Precambrian eon, Precambrian aeon, Precambrian period - the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago
--1 is a kind of eon, aeon
--1 has parts:Proterozoic, Proterozoic eon, Proterozoic aeon; Archean, Archean eon, Archean aeon, Archeozoic, Archaeozoic, Archeozoic eon, Archaeozoic aeon