Dyas

·noun A name applied in Germany to the Permian formation, there consisting of two principal groups.

dyas
dyas, ădis, f., = δυάς, the number two , Macr. Somn. Scip. 1, 6, 18; 1, 12, 5; Aug. Conf. 4, 15....

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.