swarm

Concise Oxford English Dictionary © 2008 Oxford University Press:
swarm/swɔːm/

▶noun

• 1 a large or dense group of flying insects.

  ■ a large number of honeybees that leave a hive with a queen in order to establish a new colony.

• 2 a large group of people or things.

▶verb

• 1 move in or form a swarm.

• 2 move somewhere in large numbers.

  ■ (swarm with) be crowded or overrun with.

• 3 (swarm up) climb rapidly by gripping with one's hands and feet.

– derivatives
swarmer noun.

– origin OE swearm, of Gmc origin.