What is the medical term meaning abnormally large jaw?

The medical term for an abnormally large lower jaw is prognathism. Prognathism is a condition in which the lower jaw is longer or wider than the upper jaw. The lower jaw may protrude forward, or it may be twisted to one side. Prognathism can be inherited, or it can be caused by injuries, tumors, or infections. Treatment for prognathism may involve surgery, orthodontics, or both.