In Norse mythology, Jörmungandr (Old Norse:Jǫrmungandr, pronounced [ˈjɔrmuŋɡandr̥], meaning "huge monster"), often written as Jormungand, or Jörmungand and also known as the Midgard Serpent (Old Norse: Miðgarðsormr), or World Serpent, is a sea serpent, the middle child of the giantess Angrboða and Loki. According to the Prose Edda, Odin took Loki's three children by Angrboða--the wolf Fenrir, Hel, and Jörmungandr--and tossed Jörmungandr into the great ocean that encircles Midgard. The serpent grew so large that he was able to surround the earth and grasp his own tail. As a result, he received the name of the Midgard Serpent or World Serpent. When he lets go, the world will end. Jörmungandr's arch-enemy is the god Thor. It is an example of an ouroboros.