accelerator accelerator /əkˈsɛləˌreɪtər/

noun

1. () A pedal that controls the throttle valve  ( accelerator pedal , gas pedal [ N. American] , gun , accelerator , gas [ N. American] , throttle )
   a pedal that controls the throttle valve
    He stepped on the gas
   he stepped on the gas
   
   
2. () A valve that regulates the supply of fuel to the engine  ( throttle valve , accelerator , throttle )
   a valve that regulates the supply of fuel to the engine
    You need to adjust the throttle to increase your speed
   You need to adjust the throttle to increase your speed
   
   
3. A scientific instrument that increases the kinetic energy of charged particles  ( accelerator , atom smasher , particle accelerator )
   a scientific instrument that increases the kinetic energy of charged particles
   
   
4. (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected  ( accelerator , catalyst )
   (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected