What does "extragalactic" mean?

Originating outside of the Milky Way galaxy.

What is a synonym for "extragalactic"?

Common synonyms include: alien, astral, astronomic, astronomical, astrophysical, exterrestrial.

adj

adj ·5 syllables ·Rare ·Advanced level

Adjective

1
Originating outside of the Milky Way galaxy. not-comparable
"Extragalactic astronomy is the study of things outside the Milky Way."
2
Originating outside of any galaxy. not-comparable
3
Originating outside of the local galaxy. not-comparable

Adjective

"Extragalactic stars can only be observed with optic instruments."

From extra- + galactic.