eurygnathism|jʊəˈrɪgnəθɪz(ə)m| [See -ism.] Eurygnathous character. 1890H. Ellis Criminal iii. 52 Microcephaly of the frontal region,..eurigmatism [sic; ed. 3 (1901) 50 eurignathism].1911Encycl.Brit. XXII. 424/2 Eurygnathism..is the lateral projection of jawbones so characteristic of the Mongolic races.