ball-and-socket

In this case she adopted a ball-and-socket joint—the kind by which older astronomers mounted their telescopes.

It has two arms ending in fine metal points, movable in ball-and-socket joints.

The head is joined to the atlas by a beautiful ball-and-socket joint.

It is a bath that can be rocked, or inclined in any direction, for its center rests upon a ball-and-socket joint.

In the next place, remember that all these vertebræ are fastened together by what we call ball-and-socket joints.