tumbler

One that tumbles, especially an acrobat or gymnast.

A drinking glass, originally with a rounded bottom.

A flat-bottomed glass having no handle, foot, or stem.

The contents of such a drinking glass.

A toy made with a weighted rounded base so that it can rock over and then right itself.

One of a breed of domestic pigeon that characteristically tumbles or somersaults in flight.

A piece in a gunlock that forces the hammer forward by action of the mainspring.

The part in a lock that releases the bolt when moved by a key.