definition of
cluster

[1] #1 cluster n. [bunch, clump, clustering] a grouping of a number of similar things; "a bunch of trees"; "a cluster of admirers". wn

[2] #2 cluster v. [constellate, flock, clump] come together as in a cluster or flock; "The poets constellate in this town every summer". wn

[3] #3 cluster v. [bunch, bunch up, bundle, clump] gather or cause to gather into a cluster; "She bunched her fingers into a fist". wn