swarm
noun
a moving crowd
a group of many things in the air or on the ground
“a swarm of insects obscured the light”
“clouds of blossoms”
Synonymscloud
verb
be teeming, be abuzz
“The garden was swarming with bees”
“The plaza is teeming with undercover policemen”
move in large numbers
“people were pouring out of the theater”
“beggars pullulated in the plaza”
Source: WordNet 3.1, Princeton University