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

Inflected Forms

noun

• momentums
  plural
• momenta
  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

“We are at risk of slowing down or stopping momentum on safe water solutions statewide, and that’s something that we can’t afford to stop.”

From Los Angeles Times • Jun. 10, 2026

Another issue is renewed interest in momentum trading, in which investors chase the stocks that are pushing higher.

From MarketWatch • Jun. 10, 2026

Ellen White: If they can put in a big performance against Haiti and give themselves some momentum and confidence then that can get them into the knockout rounds.

From BBC • Jun. 10, 2026

Wall Street has bought the dip, with investors piling back into momentum stocks.

From Barron's • Jun. 9, 2026

“And you were telling me about your college fair, and that was definitely better,” he said, building a momentum.

From "Anger Is a Gift" by Mark Oshiro

Related Words

• energy
• power
• strength