#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'"
  subtype:  spiral_galaxy  Great_Attractor  Magellanic_Cloud
  instance:  Milky_Way_Galaxy
  member:  star
  substance:  cosmic_dust
  member of:  universe
  supertype:  aggregation__collection__accumulation__assemblage  several things grouped together
     supertype:  group__grouping  any number of entities (members) considered as a unit
        supertype:  collection  something gathering separated things (entities/situations)
           supertype:  divisible_entity__divisibleentity  many classifications under this category are application-dependant
              supertype:  entity  something that can be "involved" in a situation
                 supertype:  thing__something___T__t___3D_or_4D_thing_or_anything_else  any category (type or individual) is instance of this type; any type is also a subtype of this type
              supertype:  divisible_thing__divisiblething
                 supertype:  thing__something___T__t___3D_or_4D_thing_or_anything_else  any category (type or individual) is instance of this type; any type is also a subtype of this type

No statement uses or specializes extragalactic_nebula; click here to add one.