deceleration

American  

[dee-sel-uh-rey-shuhn] / diˌsɛl əˈreɪ ʃən /

noun

1. the fact of losing speed, or the act of reducing the speed of something.

   Prolonged deceleration of the fetal heart rate is cause for concern.

2. the act or process of slowing the rate of increase of something.

   During that quarter, job creation stalled and stocks fell, confirming that there was a deceleration in the economy.

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Usage

What does deceleration mean? Deceleration describes a decrease in velocity, that is, momentum. Deceleration describes the slowing of an increase. Wind, for example, moves with a certain amount of momentum. When the wind’s momentum slows down, that is, the wind doesn’t blow as hard, we can say that the wind is experiencing deceleration. Example: The deceleration of the ship came abruptly to the passengers.

Other Word Forms

• nondeceleration
  noun

Etymology

Origin of deceleration

deceler(ate) ( def. ) + -ation ( def. )

Explanation

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.

Example Sentences

Medium and heavy commercial vehicles, in particular, are highly sensitive to growth deceleration, the analysts say, noting recent dealer surveys show signs of a slowdown in inquiries.

From The Wall Street Journal • May 29, 2026

The company cited macro headwinds like war and tariffs for the deceleration, saying those factors pressured the brands that make up its client base, and guided for 8% growth in the second quarter.

From The Wall Street Journal • May 27, 2026

Bank of America economist expect the latest data will show consumer spending grew by 1.4% during the first quarter—a solid pace, if a bit of a deceleration from the fourth quarter’s 1.9%.

From Barron's • Apr. 29, 2026

"To not discuss deceleration and a return to hospital was likely to be a really serious failure to provide basic medical care," he said.

From BBC • Apr. 23, 2026

I did some basic acceleration and deceleration, turned in increasingly tight circles, and even did a power-stop.

From "The Martian" by Andy Weir

Related Words

• decline
• delay
• downtrend
• downturn
• drop
• drop-off
• falloff
• slackening
• stagnation
• strike