bunion /bun″yən/ [Gk, bounion, turnip] , an abnormal, medial enlargement of the joint at the base of the great toe. It is caused by inflammation of the bursa, usually as a result of heredity, degenerative joint disease, or chronic irritation and pressure from poorly fitted shoes. It is characterized by soreness, swelling, thickening of the skin, and lateral displacement of the great toe.
