#extragalactic_nebula__extragalacticnebula__galaxy  (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'"
  supertype:  aggregation__collection__accumulation__assemblage  several things grouped together
  subtype:  spiral_galaxy  Great_Attractor  Magellanic_Cloud
  instance:  Milky_Way_Galaxy
  substance:  cosmic_dust
  member of:  universe
  member:  star  (astronomy) a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior

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