Beelzebub, a translation of Baal-zebub. Both translate to Lord of Flies (more commonly), or Lord of the Dungheap. Because flies often gather around decaying corpses and as well spread disease, the term is symbolic for Lord of
Death, Decay, Disease, etc. Beelzebub is either used as a synonym for Satan himself, or, as was made
popular in Paradise Lost, as
Satan's second-in-command devil.
You cast out devils by Beelzebub,
chief of devils. (Accusation made toward
Jesus, meaning he casts out devils by calling upon
Satan.)