Midgard is the realm of the humans in the Norse Mythology. Pictured as placed somewhere in the middle of Yggdrasil, Midgard means "the realm in the middle", or Middle-earth. Midgard is surrounded by a world of water or ocean, which is impassable.
"Middangeard" occurs half a dozen times in Beowulf.
"Midgard" is also name of a popular Open source Content management system.