(1):

(n.) A number of things of the same kind growing together; a bunch.

(2):

(n.) A number of similar things collected together or lying contiguous; a group; as, a cluster of islands.

(3):

(n.) A number of individuals grouped together or collected in one place; a crowd; a mob.

(4):

(v. t.) To collect into a cluster or clusters; to gather into a bunch or close body.

(5):

(v. i.) To grow in clusters or assemble in groups; to gather or unite in a cluster or clusters.