any of variously sized large balls used for doing exercises and for physical therapy
The stability ball is also called a balance ball, birth ball, body ball, exercise ball, fitness ball, gym ball, gymnastic ball, physioball, sports ball, Swedish ball, or therapy ball.
1995
At the end of the building is the royal tomb, consisting of a square pyramid and containing the body of Imandes.
A stick of timber is in the shape of the frustum of a square pyramid, the lower base being 22 in.
A square pyramid is placed on the top of the tower, and the whole is suitably coloured.
As this number is the square of 70, we can lay out the balls in a square, and can form a square pyramid with them.