increasing the speed of (a moving body); accelerating.

causing to develop or progress more quickly.

causing a chemical reaction to happen faster, without affecting the product of reaction.

a man who accelerates or increases the speed of something; an accelerator.

a device, such as the foot throttle of an automobile, for increasing the speed of a machine; an accelerator.

(chem.) a thing, esp. a chemical, used to speed up the rate of a chemical reaction, without undergoing a permanent chemical change; a catalyst.