the GNU version of the Collaborative International Dictionary of English
n. An intermediate shaft; esp., one which receives motion from a line shaft in a factory and transmits it to a machine.
The Century Dictionary and Cyclopedia
n. A shaft driven by a band or gearing running from another opposite and parallel shaft.
Word Usage
"Suzuki fine-tuned the R450 for 2009 by adjusting the ECU programming and cam profiles to make the engine perform even better at low - and mid-rpm range and also added a new countershaft for improved gear-shift feel."