accelerator

(noun) a pedal that controls the throttle valve. Synonyms: accelerator pedal, gas pedal, gas, throttle, gun. Examples: "He stepped on the gas."

(noun) a valve that regulates the supply of fuel to the engine. Synonyms: throttle, throttle valve.

(noun) (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected. Synonyms: catalyst.

(noun) a scientific instrument that increases the kinetic energy of charged particles. Synonyms: particle accelerator, atom smasher.