ac ‧ cel ‧ e ‧ ra ‧ tion /əkˌseləˈreɪʃ ə n/ BrE AmE noun
1 . [singular, uncountable] a process in which something happens more and more quickly
an acceleration in the rate of inflation
the rapid acceleration of economic progress in South East Asia
2 . [uncountable] the rate at which a car or other vehicle can go faster:
The latest model has excellent acceleration.
3 . [uncountable] technical the rate at which the speed of an object increases