‖n. [ L. dyas the number two. ] (Geol.) A name applied in Germany to the Permian formation, there consisting of two principal groups. [ 1913 Webster ]
a. [ Gr. syndyasmo`s a pairing, fr. syndya`zein to pair. ] Pertaining to the state of pairing together sexually; -- said of animals during periods of procreation and while rearing their offspring. Morgan. [ 1913 Webster ]