noun

1. an acrobat or gymnast who does somersaults, handsprings, etc.
2. a dog, such as a small greyhound, formerly trained to seize rabbits after attracting their attention by tumbling about acrobatically
3. a kind of pigeon that does somersaults in flight
4. 1. an ordinary drinking glass without foot or stem: orig., such a glass with a rounded or pointed bottom, that would tumble over when set down
   2. its contents
5. the part of a gunlock through which the mainspring acts upon the hammer
6. a lever, pin, etc., whose position within a lock must be changed, as by a key or dial, in order to release the bolt
7. a projecting piece, as on a revolving or rocking part, that strikes and moves another part
8. a part moving a gear into place in an automobile transmission
9. an easily tipped toy that rights itself because of the way it is weighted
10. 1. a device for tumbling laundered clothes about in hot air until they are dry
    2. tumbling box