celerity (noun) - swiftness of movement or action; rapidity [suh-ler-i-tee]
BREAKDOWN: CELER- (speed) + -ITY (quality of)
to accelerate means to go faster or speed up; to make something go faster
to decelerate means to decrease speed or slow down
“No hawk swooping down upon his prey, no stag improvising new detours by which to trick the huntsman, no dog scenting game from afar is comparable in speed to the celerity of a salesman when he gets wind a deal, to his skill in tripping up or forestalling a rival, and to the art with which he sniffs out and discovers a possible sale.” —Honore de Balzac