A cluster is a small group of people or things. When you and your friends huddle awkwardly around the snack table at a party, whispering and trying to muster enough nerve to hit the dance floor, you’ve formed a cluster.
The people seemed clustered in groups of two or three.
large stellar system-of a cluster of Milky Ways
All his grandchildren clustered around him.
cluster of flowers
Have a look at the cluster of galaxies in this photograph.
Only a tiny fracrion of the stars in our galaxy are known to occur in cluster.