Midgard (the common English transliteration of Old NorseMiðgarðr), Midjungards (Gothic), Middangeard (Old English), Middellærd (Middle English), Midgård (common Danish and Swedish) and Mittilagart (Old High German), from Proto-Germanic*medja-garda (*meddila-, *medjan-, projected PIE*medhyo-gharto), is an old Germanic name for our world, the places inhabited by men, with the literal meaning "middle enclosure". In Middle English, the name was transformed to Middellærd, Middel-erde ("Middle-earth").
Old Norse
Midgard is the realm of the humans in Norse mythology. Pictured as placed somewhere in the middle of Yggdrasil, Midgard is surrounded by a world of water or ocean, which is impassable. The ocean is inhabited by the great sea serpent Jormungand, who is so huge that he encircles the world entirely, grasping his own tail. In Norse mythology, Miðgarðr became applied to the wall around the world that the gods constructed from the eyebrows of the giant Ymir as a defence against the Jotuns who lived in Jotunheim, east of Mannheim, "the home of men," a word used to refer to the entire world (there is no direct relation to the German city of Mannheim, which is attested from the 8th century, named after an early settler called Manno).
It is depicted as an intermediate world between heaven (Asgard) and hell (Niflheim or Hel). Thus it is part of a triad of upper (Heaven), middle (Earth), and lower (Underworld). It was said to have been formed from the flesh and blood of Ymir, his flesh constituting the land and his blood the oceans, and was connected to Asgard by the Bifrost Bridge, guarded by Heimdall.
More on [ Midgard ]