momentum

American  

[moh-men-tuhm] / moʊˈmɛn təm /

noun

• momenta,
  plural
• momentums
  plural

1. 

   force or speed of movement; impetus, as of a physical object or course of events.

   The car gained momentum going downhill. Her career lost momentum after two unsuccessful films.

2. Also called linear momentum.  Mechanics. a quantity expressing the motion of a body or system, equal to the product of the mass of a body and its velocity, and for a system equal to the vector sum of the products of mass and velocity of each particle in the system.

3. Philosophy. moment.

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momentum British  

/ məʊˈmɛntəm /

noun

1.  p.  physics the product of a body's mass and its velocity See also angular momentum

2. the impetus of a body resulting from its motion

3. driving power or strength

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momentum Scientific  

/ mō-mĕn′təm /

• momenta
  plural

1. A vector quantity that expresses the relation of the velocity of a body, wave, field, or other physical system, to its energy. The direction of the momentum of a single object indicates the direction of its motion. Momentum is a conserved quantity (it remains constant unless acted upon by an outside force), and is related by Noether's theorem to translational invariance. In classical mechanics, momentum is defined as mass times velocity. The theory of Special Relativity uses the concept of relativistic mass. The momentum of photons, which are massless, is equal to their energy divided by the speed of light. In quantum mechanics, momentum more generally refers to a mathematical operator applied to the wave equation describing a physical system and corresponding to an observable; solutions to the equation using this operator provide the vector quantity traditionally called momentum. In all of these applications, momentum is sometimes called linear momentum.

2. See also angular momentum impulse

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momentum Cultural  

1. In physics, the property or tendency of a moving object to continue moving. For an object moving in a line, the momentum is the mass of the object multiplied by its velocity (linear momentum); thus, a slowly moving, very massive body and a rapidly moving, light body can have the same momentum. (See Newton's laws of motion.)

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Discover More

Figuratively, momentum can refer to the tendency of a person or group to repeat recent success: “The Bears definitely have momentum after scoring those last two touchdowns.”

Other Word Forms

Noun Inflected Forms

• momenta
  plural
• momentums
  plural

Etymology

Origin of momentum

First recorded in 1690–1700; from Latin mōmentum; see moment

Explanation

Momentum is generally used to mean increasing forward motion. A boulder rolling down a hill gains momentum. So does a great idea, a team on a winning streak, or the economy. To find an object's physical momentum you multiply its mass by its velocity. Determining the momentum of the economy or the latest fad is much more difficult. Used figuratively, momentum implies that, like a boulder rolling down a hill, something with momentum will continue moving forward on its own. If you're running for class president, you might want to build momentum by holding a few rallies, passing out flyers and starting a website. Once you have momentum, your opponents won't be able to stop you.

Example Sentences

See Examples For:

momentum momenta momentums

Its momentum initially drives ash outwards in every direction – spreading hundreds of kilometers before high-altitude winds take over and carry fine ash thousands of kilometers downwind within a day.

From Science Daily ● Sep. 22, 2026

This momentum is supported by increasing contribution from mainland Chinese employees in Hong Kong, the analyst says.

From The Wall Street Journal ● Sep. 22, 2026

But who could resist the ecstatic momentum of her ad hoc band members buying into her grassroots dream?

From Los Angeles Times ● Sep. 22, 2026

AT&T’s stock has struggled for momentum this year, but with various challenges now well understood by the market, one analyst thinks it’s set to gain.

From MarketWatch ● Sep. 21, 2026

Grub squealed as he was released, his newfound momentum carrying him directly into three of his comrades.

From "Artemis Fowl" by Eoin Colfer

Romping the go-pedal at highway speeds initiates a wild, jaw-clenching acceleration event, a Nantucket sleigh ride of instantaneous momenta.

From The Wall Street Journal ● Sep. 5, 2026

The angular momenta tied to its lattice vibrations combined in a way that produced a new rotation moving at twice the frequency but in the opposite direction.

From Science Daily ● May 24, 2026

For example, such measurements are made with detectors at the Large Hadron Collider or instruments called mass spectrometers that use such information to calculate the masses and momenta of particles, ions and molecules.

From Scientific American ● Oct. 21, 2021

Physicists once assumed that if you inverted all the particles’ positions—swapping left and right, up and down, forward and back—and reverse all their momenta, the universe should work just the same.

From Science Magazine ● Feb. 5, 2021

I shall now proceed to exhibit the several momenta of this solution, and to consider them in their order.

From The Critique of Pure Reason by John Miller Dow Meiklejohn

"Differing momentums appear at different positions on the detector. Put more simply, the different directions in which the electrons move in a layer are represented by corresponding dots on the detector," said Elmers.

From Science Daily ● Feb. 15, 2024

He says he rarely questions the root of his attraction to cars, the solitary driver and the twin momentums of fate and purpose.

From Los Angeles Times ● Nov. 15, 2023

But after their six years together individual momentums are forcing a group hiatus.

From New York Times ● Jul. 27, 2012

Although clocking at 40 minutes, you will find just seven post-rock songs that go from slow psychedelic notes to big momentums of distortion, noise and epic choruses.

From The Guardian ● Aug. 17, 2011

He did not like chromo-lithographs, or the framed photographs which Mrs. Alwynn called her "momentums of travel," among his rare old prints, either.

From The Danvers Jewels, and Sir Charles Danvers by Mary Cholmondeley

Related Words

• energy
• power
• strength