[tum.bler] n (14c) 1: one that tumbles: as a: one that performs tumbling feats: acrobat b: any of various domestic pigeons that tumble or somersault backward in flight or on the ground
2: a drinking glass without foot or stem and orig. with pointed or convex base 3 a: a movable obstruction in a lock (as a lever, latch, wheel, slide, or pin) that must be adjusted to a particular position (as by a key) before the bolt can be thrown b: a piece on which the mainspring acts in a gun's lock
4: a device or mechanism for tumbling (as a revolving cage in which clothes are dried)
5: a worker that operates a tumbler -- tum.bler.ful n