galaxy; island universe
Astronomical term; historically used to describe galaxies as separate 'island universes' before the modern understanding of galaxies was fully established. Now somewhat dated but still encountered in older texts and poetic contexts.
The Andromeda Galaxy was once called an island universe.
The term 'island universe' poetically expresses the vastness of the cosmos.
Compound of 島 (island) and 宇宙 (universe), calque of English 'island universe', a historical term for galaxies.