1 : to move faster : to gain speed
She stepped on the gas and the car accelerated.
The plane accelerated down the runway.
She stepped on the gas and accelerated the car.
2 : to cause (something) to happen sooner or more quickly
He says that cutting taxes will help to accelerate economic growth.
Conditions accelerated our departure. (=conditions caused us to depart sooner]
The rate of economic growth has continued to accelerate.
— accelerated adjective
Changes have occurred at an accelerated pace/rate.
She’s taking an accelerated course in English. (=a course in which English is taught at a faster pace than usual]
— accelerating adjective
an accelerating rate