Priscoan
n 1: the earliest eon in the history of the Earth from the first
accretion of planetary material (around 4,600 million years
ago) until the date of the oldest known rocks (about 3,800
million years ago); no evidence of life [syn: {Hadean},
{Hadean time}, {Hadean eon}, {Hadean aeon}, {Priscoan},
{Priscoan eon}, {Priscoan aeon}]