n 1: a pedal that controls the throttle valve; "he stepped on the
gas" [syn: accelerator pedal, gas pedal, gas, throttle, gun]
2: a valve that regulates the supply of fuel to the engine
[syn: throttle, throttle valve]
3: (chemistry) a substance that initiates or accelerates a
chemical reaction without itself being affected [syn: catalyst]
[ant: anticatalyst]
4: a scientific instrument that increases the kinetic energy of
charged particles [syn: particle accelerator, {atom
smasher}]