WordNet sense 1 ((often followed by `of') a large number or amount or extent):

batch, deal, heap, lot, mass, mess, mint, peck, pile, plenty, pot, raft, sight, slew, spate, stack, wad, hatful, mickle, muckle, good deal, great deal, quite a little, tidy sum, whole lot, whole slew

WordNet sense 2 (an orderly crowd):

troop

WordNet sense 3 (a group of sheep or goats):

fold

WordNet sense 4 (come together as in a cluster or flock):

clump, cluster, constellate