Swarm
Part of speech: noun
Definition: A large number of insects, especially when in motion or (for bees) migrating to a new colony. A mass of people or animals in turmoil.
Part of speech: verb
Definition: To move as a swarm. To teem, or be overrun with insects. To fill a place as a swarm. To overwhelm as by an opposing army. To climb by gripping with arms and legs.
Horde
Part of speech: noun
Definition: A wandering troop or gang; especially, a clan or tribe of a nomadic people (originally Tatars) migrating from place to place for the sake of pasturage, plunder, etc.; a predatory multitude.A large number of people.