swarm

(noun) a moving crowd. Synonyms: drove, horde.

(noun) a group of many things in the air or on the ground. Synonyms: cloud. Examples: "A swarm of insects obscured the light." "Clouds of blossoms." "It discharged a cloud of spores."

(verb) be teeming, be abuzz. Synonyms: teem, pullulate. Examples: "The garden was swarming with bees." "The plaza is teeming with undercover policemen." "Her mind pullulated with worries."

(verb) move in large numbers. Synonyms: pour, stream, teem, pullulate. Examples: "People were pouring out of the theater." "Beggars pullulated in the plaza."