(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'"
(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''"
(astronomy) a collection of star systems; any of the billions of systems each having many stars and nebulae and dust