1911 Encyclopædia Britannica/Prognathism

PROGNATHISM (Gr. πρό, forward, and γνάθος, jaw), the term applied by ethnologists, with its opposite Orthognathism (ὀρθός, straight), to describe the varying degrees of projection of the upper jaw, which itself is determined by the angle made by the whole face with the brain-cap. Eurygnathism (εὐρύς, wide), is the lateral projection of jawbones so characteristic of the Mongolic races. (See Craniometry.)