Definition of "Galaxy" :

noun: a splendid assemblage (especially of famous people)

noun: (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'."

noun: 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