What term describes a collection of hundreds of billions of stars clustered together by gravity?

A galaxy is defined as a massive system that contains hundreds of billions of stars, along with gas, dust, and dark matter, all held together by gravity. Galaxies can vary significantly in size, structure, and composition, and they are the fundamental building blocks of the universe. Each galaxy can contain star systems, clusters, and nebulae, among other celestial objects.

The term "cluster" refers to a group of galaxies that are held together by gravity and is not limited to the collection of stars alone. The "solar system" is a more localized system, specifically representing a collection of planets and other objects that orbit a single star, such as our Sun. The "universe" encompasses everything, including all galaxies, clusters, and cosmic structures, but it is a much larger and overarching term than that used to describe individual collections of stars. This clarity helps to distinguish the specific term used to describe the vast collections of stars we observe throughout space.