Read the dictionary definition of galaxy. All definitions for this word.
1. a splendid assemblage (especially of famous people)
2. (astronomy) a collection of star systems; any of the billions of systems each having many stars and nebulae and dust
1. `extragalactic nebula' is a former name for `galaxy'
3. tufted evergreen perennial herb having spikes of tiny white flowers and glossy green round to heart-shaped leaves that become coppery to maroon or purplish in fall