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. [from 18th c.]
The act of braking, of using a brake to slow down a machine or vehicle
(engineering) An apparatus for testing the power of a steam engine or other motor by weighing the amount of friction that the motor will overcome; a friction brake.