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

“Emerging Markets continued to deliver despite the Chinese condom headwinds still persisting with broad-based momentum extending well beyond China,” they said.

From The Wall Street Journal ● Jul. 29, 2026

Modi, whose political rise has long been intertwined with social media, joined the digital battle with selfie-style videos and direct appeals to young people as the protests gathered momentum.

From BBC ● Jul. 29, 2026

"As these investments are supported by revenue generated from AI services, the momentum in memory demand is expected to persist."

From Barron's ● Jul. 28, 2026

Still, it is worth putting the software sector’s recent momentum into perspective.

From MarketWatch ● Jul. 28, 2026

Any momentum we gained is dispelled by the surface we land on.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer

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

But it rides on a brilliantly tuned air suspension with adaptive dampers to tie down rebellious momenta.

From The Wall Street Journal ● Nov. 24, 2025

Because the particles’ final energies and momenta contain information about what they encountered on their journey through the nucleus, they can also help uncover what’s happening in the hidden hearts of atoms.

From Scientific American ● Apr. 27, 2023

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

As it is important that we should have a clear view of the character of the ether, we will revert to the principle we have advocated, viz.: that in equal spaces there are equal momenta.

From Outlines of a Mechanical Theory of Storms Containing the True Law of Lunar Influence by Bassnett, Thomas

"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

They may, notwithstanding, be very unequal in weight, but they must be so situated, that, if set in motion, their momentums would be equal.

From Conversations on Natural Philosophy, in which the Elements of that Science are Familiarly Explained by Jones, Thomas P.

Related Words

• energy
• power
• strength