A protuberance is a body part that protrudes (bulges) outward from a surface.
For example, the ankle is a protuberance of the leg. The ears protrude from the head.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.