deceleration

/dɪˌsɛləˈreɪʃən/

Other forms: decelerations

Deceleration is a slowing down: the unexpected deceleration of your car might mean that you've run out of gas.

Use the noun deceleration when you talk about a gradual decrease in speed. When you're on a Ferris wheel, its deceleration tells you that the ride is almost over, and the deceleration of a train at a railroad crossing happens for safety reasons. The opposite of deceleration is acceleration, or speeding up. The word deceleration was originally an 1890's railroad term, constructed by adding de, or "the opposite of" to acceleration.

Definitions of deceleration

1. noun

   a decrease in rate of change
   “the deceleration of the arms race”

   synonyms: retardation, slowing

   antonyms:

   acceleration

   an increase in rate of change

   type of:

   alteration, change, modification

   an event that occurs when something passes from one state or phase to another
2. noun

   the act of decelerating; decreasing the speed
   “he initiated deceleration by braking”

   antonyms:

   acceleration

   the act of accelerating; increasing the speed

   type of:

   hurrying, speed, speeding

   changing location rapidly
3. noun

   (physics) a rate of decrease in velocity
   antonyms:

   acceleration

   (physics) a rate of increase of velocity

   type of:

   rate

   a magnitude or frequency relative to a time unit