cluster in WordNet English dictionary

1. a grouping of a number of similar things
   "a bunch of trees"; "a cluster of admirers"
   bunch  clump  cluster  clustering 
   

1. gather or cause to gather into a cluster
   "She bunched her fingers into a fist"
   bunch  bunch up  bundle  cluster  clump 
   
2. come together as in a cluster or flock
   "The poets constellate in this town every summer"
   cluster  constellate  flock  clump