Main entry: speed, speed up, accelerate, quicken
Definition: move faster
Usage: The car accelerated
Antonyms: retard, slow, slow down, slow up, decelerate
Definition: lose velocity; move more slowly
Main entry: accelerate, speed, speed up
Definition: cause to move faster
Usage: He accelerated the car
Antonyms: slow down, decelerate
Definition: reduce the speed of