n (obsolete) The winch of a crossbow. (defdate|14th-19th c.)
n (context|chiefly|_|nautical) The handle of a pump.
n A device used to slow or stop the motion of a wheel, or of a vehicle, by friction; also, the controls or apparatus used to engage such a mechanism such as the pedal in a car. (defdate|from 18th c.)
n (figuratively) Something used to retard or stop some action, process etc.
n The act of braking, of using a brake to slow down a machine or vehicle