galaxy

American  

[gal-uhk-see] / ˈgæl ək si /

noun

plural

galaxies

1. Astronomy.

   1. a large system of stars held together by mutual gravitation and isolated from similar systems by vast regions of space.

   2. Often the galaxy or the Galaxy the system of stars in which the earth and the sun are located; the Milky Way.

2. any large and brilliant or impressive assemblage of people or things.

   Guests at the party included a whole galaxy of opera stars.

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Galaxy ¹ British  

/ ˈɡæləksɪ /

noun

1. Also known as: the Milky Way System.  the spiral galaxy, approximately 100 000 light years in diameter, that contains the solar system about three fifths of the distance from its centre See also Magellanic Cloud

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galaxy ² British  

/ ˈɡæləksɪ /

noun

1. Former names: island universe.   extragalactic nebula.  any of a vast number of star systems held together by gravitational attraction in an asymmetric shape (an irregular galaxy ) or, more usually, in a symmetrical shape (a regular galaxy ), which is either a spiral or an ellipse

2. a splendid gathering, esp one of famous or distinguished people

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galaxy Scientific  

/ găl′ək-sē /

1. Any of numerous large-scale collections of stars, gas, and dust that make up the visible universe. Galaxies are held together by the gravitational attraction of the material contained within them, and most are organized around a galactic nucleus into elliptical or spiral shapes, with a small percentage of galaxies classed as irregular in shape. A galaxy may range in diameter from some hundreds of light-years for the smallest dwarfs to hundreds of thousands of light-years for the largest ellipticals, and may contain from a few million to several trillion stars. Many galaxies are grouped into clusters, with the clusters themselves often grouped into larger superclusters.

2. See more at active galaxy See also elliptical galaxy irregular galaxy lenticular galaxy spiral galaxy

3. the Galaxy. The Milky Way.

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galaxy Cultural  

1. A large, self-contained mass of stars.

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Discover More

A common form for galaxies is a bright center with spiral arms radiating outward.

The sun belongs to the galaxy called the Milky Way.

The universe contains billions of galaxies.

Etymology

Origin of galaxy

First recorded in 1350–1400; Middle English galaxie, galaxias, from Medieval Latin galaxia, galaxias, ultimately from Greek galaxías kýklos “the Milky Way”; cycle, galacto-

Explanation

A galaxy is a collection of stars and planets that are held together by gravity. In a galaxy, the celestial bodies rotate around a central object. The Earth's galaxy is known as the Milky Way. Our solar system, made up of the Sun and the planets that encircle it, is a tiny part of that galaxy. A galaxy can also refer to a gathering of a lot of sparkly people –– like celebrities or sports stars. What gravity holds this galaxy together? Usually cameras.

Example Sentences

The combination of renewed activity, enormous scale, and strong environmental influence makes this galaxy an important example of how galaxies evolve.

From Science Daily • Apr. 13, 2026

These include Cepheid variable stars, which brighten and dim in predictable ways, red giant stars with known brightness, Type Ia supernovae, and certain galaxy types.

From Science Daily • Apr. 12, 2026

To better understand the origin of this signal, scientists look beyond our galaxy.

From Science Daily • Apr. 10, 2026

Instead, it formed in a nearby companion galaxy and later moved into the Milky Way.

From Science Daily • Apr. 4, 2026

“Also, it turns out the visible mass of a galaxy doesn’t have enough gravity to explain why it doesn’t fly apart.”

From "The Sun Is Also a Star" by Nicola Yoon