prognathy|ˈprɒgnəθɪ| [f. as prognath-ous + -y: cf.anomal-ous, anomal-y, infam-ous, infam-y.] = prognathism. 1890H. M. Stanley Darkest Africa I. xiv. 352 With slight prognathy of jaws.1894Cosmopolitan XVII. 43 Their features are mostly regular without that..marked prognathy of the true negro.