- galaxy, 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'"
--1 is a kind of collection, aggregation, accumulation, assemblage
--1 is a member of
--1 has members: staruniverse, existence, creation, world, cosmos, macrocosm
--1 has substances: cosmic dust
--1 has particulars:spiral galaxy, spiral nebula; Great Attractor; Magellanic Cloud; Milky Way, Milky Way Galaxy, Milky Way System