ac ‧ cel ‧ e ‧ ra ‧ tor /əkˈseləreɪtə $ -ər/ BrE AmE noun [countable]
1 . the part of a car or other vehicle that you press with your foot to make it go faster SYN gas pedal American English
2 . technical a large machine used to make extremely small pieces of ↑ matter 1 (3) move at extremely high speeds