noun (n)

• a pedal that controls the throttle valve(noun.artifact)

  Synonym:
  accelerator pedal, gas, gas pedal, gun, throttle
  

  source: wordnet30
• a valve that regulates the supply of fuel to the engine(noun.artifact)

  Synonym:
  throttle, throttle valve
  

  source: wordnet30
• (chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected(noun.substance)

  Synonym:
  catalyst
  Antonym:
  anticatalyst
  

  source: wordnet30
• a scientific instrument that increases the kinetic energy of charged particles(noun.artifact)

  Synonym:
  atom smasher, particle accelerator
  

  source: wordnet30
• One who, or that which, accelerates. Also as an adj.; as, accelerator nerves.(noun)

  source: webster1913