The Collaborative International Dictionary of English v.0.48:

Accelerator \Ac*cel"er*a`tor\, n.
   One who, or that which, accelerates. Also as an adj.; as,
   accelerator nerves.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "accelerator":
   PCV valve, alternator, ammeter, atom smasher, atomic accelerator,
   atomic cannon, bearings, bonnet, boot, brake, bucket seat, bumper,
   camshaft, carburetor, chassis, choke, clutch, connecting rod,
   convertible top, cowl, crank, crankcase, crankshaft, cutout,
   cylinder, cylinder head, dash, dashboard, differential,
   distributor, exhaust, exhaust pipe, fan, fender, flywheel, gear,
   gearbox, gearshift, generator, headlight, headrest, hood, horn,
   ignition, intake, manifold, muffler, parking light,
   particle accelerator, piston, power brakes, power steering,
   radiator, rear-view mirror, seat belt, shock absorber, spark plug,
   speedometer, springs, starter, steering wheel, top, transmission,
   universal, valve, windscreen, windshield



The Free On-line Dictionary of Computing (30 December 2018):

accelerator

    Additional hardware to perform some function faster
   than is possible in software running on the normal CPU.
   Examples include graphics accelerators and floating-point
   accelerators.

   (1994-11-08)