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.
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.