(n) the eon following the Hadean time and preceding the Phanerozoic eon; from about 3, 800 million years ago until 544 million years ago, Syn. Precambrian aeon, Precambrian eon, Precambrian period
a. 1. (Geog.) Of or pertaining to Cambria or Wales. [ 1913 Webster ]
2. (Geol.) Of or pertaining to the lowest subdivision of the rocks of the Silurian or Molluscan age; -- sometimes described as inferior to the Silurian. It is named from its development in Cambria or Wales. See the Diagram under Geology. [ 1913 Webster ]