deceleration

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
    see moresee less
    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”
    see moresee less
    Antonyms:
    acceleration, quickening, speedup
    the act of accelerating; increasing the speed
    type of:
    hurrying, speed, speeding
    changing location rapidly
  3. noun
    (physics) a rate of decrease in velocity
    see moresee less
    Antonyms:
    acceleration
    (physics) a rate of increase of velocity
    type of:
    rate
    a magnitude or frequency relative to a time unit
Word Family