center of mass

American  

noun

Mechanics.

1. the point at which the entire mass of a body may be considered concentrated for some purposes; formally, the point such that the first moment of a physical or geometric object about every line through the point is zero.

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center of mass Scientific  

1. A point in space determined by a distribution of mass (such as a solid object, a collection of objects, or a gas), such that a uniform force acting on the whole distribution acts as if the distribution were located at just that point. For example, the gravitational force on Earth attracts small objects as if it were pulling them from their center of mass (in this case, the center of mass is also called the center of gravity). Two stars in orbit around each other revolve around their collective center of mass.

2. See also barycenter

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Etymology

Origin of center of mass

First recorded in 1875–80

Compare meaning

How does center-of-mass compare to similar and commonly confused words? Explore the most common comparisons:

• center of mass vs. center of gravity

Example Sentences

Positronium is a short-lived, two-body system made up of an electron and a positron bound together and orbiting a shared center of mass.

From Science Daily • Apr. 28, 2026

Shifting the center of mass rearward dramatically improved the Corvette’s balance and hotshot acceleration.

From The Wall Street Journal • Dec. 18, 2025

When a skateboarder hits the circular section of the half-pipe, they start crouched down, positioning their center of mass further from the center of rotation above their head.

From Los Angeles Times • Aug. 5, 2024

Eventually, when its nuclear batteries run out of juice for good, it will continue to quietly orbit the center of mass of the Milky Way for eternity.

From Salon • May 7, 2023

Seven mighty green tractors would lash out, seize an attacking sphere, and snap it into the center of mass of the unit of seven.

From Spacehounds of IPC by Smith, E. E. (Edward Elmer)