1 collection, bunch, clutch, tuft, bundle:
Notice that cluster of flowers near the top of the plant.
2 collection, bunch, group, knot, body, band, company, gathering, crowd, assembly, congregation, throng, flock, assemblage, swarm:
A cluster of well-wishers stood talking with the minister.
3 collect, bunch, group, band, gather, crowd, congregate, throng, assemble, accumulate, mass, aggregate:
A number of people clustered round the new sculpture. Why do these flowers cluster at this tree?