/ Dictionary / Index T tumbler gear: Meaning and Definition of Find definitions for: tum'bler gear" Pronunciation: [key] — Mach. Mach. a transmission having gears actuated by a tumbler. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. tumbler tumbleweed Related Content Daily Word Quiz: agitated Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language