Tumbler

tumbler
1. One who tumbles; one who plays tricks by various motions of the body; an acrobat.
2. A movable obstruction in a lock, consisting of a lever, latch, wheel, slide, or the like, which must be adjusted to a particular position by a key or other means before the bolt can be thrown in locking or unlocking.
3. A piece attached to, or forming part of, the hammer of a gunlock, upon which the mainspring acts and in which are the notches for sear point to enter.
4. A drinking glass, without a foot or stem; so called because originally it had a pointed or convex base, and could not be set down with any liquor in it, thus compelling the drinker to finish his measure.
5. (Science: zoology) A variety of the domestic pigeon remarkable for its habit of tumbling, or turning somersaults, during its flight.
6. (Science: zoology) A breed of dogs that tumble when pursuing game. They were formerly used in hunting rabbits.
7. A kind of cart; a tumbrel.