Pronunciation: (tum'blur),[key] —n. 1. a person who performs leaps, somersaults, and other bodily feats.
2. (in a lock) any locking or checking part that, when lifted or released by the action of a key or the like, allows the bolt to move.
3. a stemless drinking glass having a flat, often thick bottom.
4. (in a gunlock) a leverlike piece that by the action of a spring forces the hammer forward when released by the trigger.
5. Mach. a. a part moving a gear into place in a selective transmission.
b. a single cog or cam on a rotating shaft, transmitting motion to a part with which it engages.
6. a tumbling box or barrel.
7. a person who operates a tumbling box or barrel.
8. one of a breed of dogs resembling a small greyhound, used formerly in hunting rabbits.
9. Also called roller. one of a breed of domestic pigeons noted for the habit of tumbling backward in flight.
10. a toy, usually representing a fat, squatting figure, that is weighted and rounded at the bottom so as to rock when touched.
11. a tumbrel or tumble cart.