intransitive. Of bees: To gather in a compact cluster and leave the hive in a body to found a new colony: see swarm, n. 1. Also with off.

Of bees: To throw off (a swarm); generally absol. to swarm. (The ordinary term in Scottish.)

intransitive. Of bees: To cluster together in a mass. Now dialect.

Scottish. Of bees: To swarm. Cf. cast, v. 22.