extragalactic nebula

Thesaurus

Noun

1.

extragalactic nebula - (astronomy) a collection of star systems; any of the billions of systems each having many stars and nebulae and dust; "`extragalactic nebula' is a former name for `galaxy'" galaxy astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole aggregation, collection, accumulation, assemblage - several things grouped together or considered as a whole spiral galaxy, spiral nebula - a galaxy having a spiral structure; arms containing younger stars spiral out from old stars at the center Great Attractor - a massive grouping of galaxies in the direction of Centaurus and Hydra whose gravitational attraction is believed to cause deviations in the paths of other galaxies Milky Way, Milky Way Galaxy, Milky Way System - the galaxy containing the solar system; consists of millions of stars that can be seen as a diffuse band of light stretching across the night sky star - (astronomy) a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior cosmos, macrocosm, universe, world, existence, creation - everything that exists anywhere; "they study the evolution of the universe"; "the biggest tree in existence" cosmic dust - clouds of particles or gases occurring throughout interstellar space