| Noun | 1. | cotyloid joint - a freely moving joint in which a sphere on the head of one bone fits into a rounded cavity in the other bonearticulatio humeri, shoulder joint, shoulder - a ball-and-socket joint between the head of the humerus and a cavity of the scapula articulatio coxae, coxa, hip joint, hip - the ball-and-socket joint between the head of the femur and the acetabulum |