Accelerator

• Device which quickens the operation of an expression mechanism, altering a crescendo, decrescendo, or other volume level change from slow to fast.
• A device for increasing the speed of a motor vehicle engine.
• The foot pedal the makes the car go faster.
• a valve that regulates the supply of fuel to the engine
• a scientific instrument that increases the kinetic energy of charged particles
• One who, or that which, accelerates; A device for causing acceleration; A substance which speeds up chemical reactions.