mumblety-peg

Ginglymoid and ginglyform are infrequently invoked anatomical terms that derive from the Greek γίγγλυμος for a hinge. These skeletal structures refer and describe specifically to the type of joint that permits movement along one plane only—like the knees and elbow, differentiated from the ball-and-socket joints of the hips and shoulders, which were dubbed synovial by Paracelsus, most likely arbitrarily.