Deceleration

['diː,selə'reɪʃən] or [di,sɛlə'reʃən]

(noun.) the act of decelerating; decreasing the speed; 'he initiated deceleration by braking'.

(noun.) a decrease in rate of change; 'the deceleration of the arms race'.

(noun.) (physics) a rate of decrease in velocity.

Typist: Sophie--From WordNet