deceleration

American

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

noun

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.
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.

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. )

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The company’s guidance points to a deceleration in growth amid competition with ByteDance’s Soda Music, Su says.

From The Wall Street Journal • Mar. 19, 2026

A Wall Street Journal poll forecasts a slowdown in retail sales growth to 3% on the year over January-February, alongside a sharp deceleration in FAI to 0.8%.

From The Wall Street Journal • Mar. 13, 2026

Analysts project fourth-quarter product revenue to increase 27% year-over-year, a slight deceleration from 29% in Q3.

From Barron's • Feb. 25, 2026

EU.S. real GDP grew 1.4% in Q4 2025, a deceleration from the 4.4% growth in Q3.

From Barron's • Feb. 19, 2026

As black changed to bright, so also did weightlessness give way to deceleration.

From "Flying to the Moon: An Astronaut's Story" by Michael Collins

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023