synchromesh

from WordNet (r) 3.0 (2006)

synchromesh
    n 1: an automotive system for shifting gears in which the gears
         revolve at the same speed and so shift smoothly

from Moby Thesaurus II by Grady Ward, 1.0

22 Moby Thesaurus words for "synchromesh":
      Hydromatic, automatic transmission, cogwheel, differential,
      differential gear, freewheel, gear, gear train, gearbox, gearing,
      gearshift, gearwheel, high, intermediate, low, neutral, overdrive,
      rack, reverse, standard transmission, stick shift, transmission