D defs.my
Entry 1 sense Webster, 1913

Geosynclinal

· Ge·o·syn·cli·nal · IPA
01 n. the downward bend or subsidence of the earth's crust, which allows of the gradual accumulation of sediment, and hence forms the first step …
  1. 1.
    the downward bend or subsidence of the earth's crust, which allows of the gradual accumulation of sediment, and hence forms the first step in the making of a mountain range; -- opposed to geanticlinal.(Geol.)