noun.
One who or that which accelerates; a hastener.
noun.
A device in a motor-car by which the operator may render inoperative the speed governor of the motor. If the governor is of the centrifugal type, as the speed increases the balls or weights fly outward against the action of a spring. The accelerator increases the tension of the spring or draws the balls inward directly, so that the governor ceases to act to close the throttle or regulate speed as the motor increases its number of revolutions above the limit set by the normal tension of the springs.