[n] a valve that regulates the supply of fuel to the engine
[n] a scientific instrument that increases the kinetic energy of charged particles
[n] a pedal that controls the throttle valve; "he stepped on the gas"
[n] (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected
\Ac*cel"er*a`tor\, n. One who, or that which, accelerates. Also as an adj.; as, accelerator nerves.