ˈsüpəˌnād.ə(r) noun
( -s )
Etymology: New Latin, from Latin supinatus + -or
: a muscle that produces the motion of supination ; specifically : a deeply situated muscle of the forearm that arises in two layers from the lateral epicondyle of the humerus and adjacent parts of the ligaments and bones of the elbow and passing over the head of the radius is inserted into its neck and the lateral surface of its shaft