a person or thing that accelerates.
Automotive. a device, usually operated by the foot, for controlling the speed of an engine.
British. any two- or three-wheeled motor vehicle, as a motorcycle or motor scooter.
Photography. a chemical, usually an alkali, added to a developer to increase the rate of development.
Also called accelerant. Chemistry. any substance that increases the speed of a chemical change, as one that increases the rate of vulcanization of rubber or that hastens the setting of concrete, mortar, plaster, or the like.
Anatomy, Physiology. any muscle, nerve, or activating substance that quickens a movement.
Also called atom smasher, particle accelerator. Physics. an electrostatic or electromagnetic device, as a cyclotron, that produces high-energy particles and focuses them on a target.

1605–15; 1930–35 for def 7; accelerate + -or2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
accelerator (ækˈsɛləˌreɪtə)
1.  a device for increasing speed, esp a pedal for controlling the fuel intake in a motor vehicle; throttle
2.  physics Also called (not in technical usage): atom smasher a machine for increasing the kinetic energy of subatomic particles or atomic nuclei and focusing them on a target
3.  chem a substance that increases the speed of a chemical reaction, esp one that increases the rate of vulcanization of rubber, the rate of development in photography, the rate of setting of synthetic resins, or the rate of setting of concrete; catalyst
4.  economics (in an economy) the relationship between the rate of change in output or sales and the consequent change in the level of investment
5.  anatomy a muscle or nerve that increases the rate of a function

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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Word Origin & History

1610s, from L. agent noun use of accelerare (see accelerate). Motor vehicle sense is from 1900.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

accelerator ac·cel·er·a·tor (āk-sěl'ə-rā'tər)

  1. One that increases rapidity of action or function.

  2. A nerve, muscle, or substance that quickens movement or response.

  3. A catalyst.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Computing Dictionary

accelerator definition

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.
The Free On-line Dictionary of Computing, © Denis Howe 2010
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Encyclopedia Britannica


in the rubber industry, any of numerous chemical substances that cause vulcanization (q.v.) of rubber to occur more rapidly or at lower temperatures. Many classes of compounds act as accelerators, the most important being organic materials containing sulfur and nitrogen, especially derivatives of benzothiazole.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
But an exploding star can be expected to have produced also some more energetic
  particles than a mere human-built accelerator.
To produce these high-energy photons, they used a device called a linear
It can only be done by bouncing photons off a high energy beam of electrons
  circulating in a particle accelerator.
In some instances, it's been reported, drivers have mistakenly continued to
  press the accelerator for up to twelve seconds.
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