D defs.my
Entry 1 sense Webster, 1913

Dyas

/dī'-əs/ · Dy·as · IPA /dˈaɪəs/
01 n. A name applied in Germany to the Permian formation, there consisting of two principal groups.
  1. 1.
    A name applied in Germany to the Permian formation, there consisting of two principal groups.(Geol.)