n. 1. One who tumbles; one who plays tricks by various motions of the body; an acrobat. [ 1913 Webster ] 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. [ 1913 Webster ] 3. (Firearms) 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 the sear point to enter. [ 1913 Webster ] 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. [ 1913 Webster ] 5. (Zool.) A variety of the domestic pigeon remarkable for its habit of tumbling, or turning somersaults, during its flight. [ 1913 Webster ] 6. (Zool.) A breed of dogs that tumble when pursuing game. They were formerly used in hunting rabbits. [ 1913 Webster ] 7. A kind of cart; a tumbrel. [ Prov. Eng. & Scot. ] [ 1913 Webster ] | 