Noun
supercluster (plural superclusters)
(astronomy) An extended group of clusters of galaxies
In a redshift map, galaxies in front of a supercluster have excess radial velocities towards it and have redshifts slightly higher than their distance would imply, while galaxies behind the supercluster have redshifts slightly low for their distance. Source: Internet
It contains the Perseus supercluster and it spans about a billion light-years, making it one of the largest known structures in the universe. Source: Internet