According to Wikipedia, a rogue star or intergalactic star is
not gravitationally bound to a galaxy.
But according to a citation on the same Wikipedia page, the first intergalactic stars were discovered in the Virgo cluster of galaxies.
These stars form a massive group aproximately 300,000 light years away from the nearest galaxy.
Is there any clear, stated definition which differentiates galaxies from "massive groups of rogue stars"?