anchylosis /(ăṉ`kĭ*lō"sĭs)/

an·chy·lo·sis

anchylosis

n.
  1. The process of formation of a stiff joint; also, the abnormal adhesion and rigidity of the bones of a joint which has become stiff. (Med.)
  2. The union of two or more separate bones to from a single bone; the close union of bones or other structures in various animals. (Anat.)