1610s, from Latin accelerator, agent noun from accelerare (see accelerate). Motor vehicle sense is from 1900.
accelerator ac·cel·er·a·tor (āk-sěl'ə-rā'tər)
n.
One that increases rapidity of action or function.
A nerve, muscle, or substance that quickens movement or response.
A catalyst.
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.