Tumbler

Noun

1. One who tumbles; one who plays tricks by various motions of the body.
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 rotating device for smoothing and polishing rough objects, placed inside it, on relatively small parts.
4. 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.
5. A drinking glass that has no stem, foot, or handle — so called because such glasses originally had a pointed or convex base and could not be set down without spilling. This compelled the drinker to finish their measure.