Lord Krishna's another name is MURARI meaning Destroyer of demon Mura.

MURA was a great demon who had seven thousand sons.

He was an ally of the demon Naraka, who ruled over Pragjyotisha, and assisted him in the defence of that city against Krishna.

He placed in the environs of that city "nooses the edges of which were sharp as razors," but Krishna cut them to pieces with is discus, slew Muru, "and burnt his seven thousand sons like moths with the flame of the edge of his discus."

Since Lord Krishna destroyed Demon Mura he is called Murari

Mura=Name of the demon Mura
Ari=Enemy
Murari=Enemy of demon Mura