deceleration
Americannoun
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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
Etymology
Origin of deceleration
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.
Vocabulary lists containing deceleration
Force and Motion (Mechanics) - Middle School
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Force and Motion (Mechanics) - Introductory
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Physics - Introductory
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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 monetary authority said that a combination of higher inflation expectations and a deceleration of economic activity presented a challenging landscape for monetary policy.
From The Wall Street Journal ● Nov. 4, 2026
It is during this stage that the remaining rock begins shrinking rapidly and experiences substantial deceleration.
From Science Daily ● Oct. 29, 2026
Prada reported a deceleration in sales growth as luxury companies struggle to spark renewed demand for high-end goods.
From The Wall Street Journal ● Oct. 23, 2026
Rising worries about the cost and availability of funding for companies has pushed investors to cut equity-market exposure to those AI companies and price in a deceleration of earnings growth, noted Goldman.
From MarketWatch ● Oct. 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
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Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
