Asgard is one of the Nine Worlds in Norse mythology.
Asgard is, of course, home to all the Marvel panoply of gods, but, interestingly, its name carries the meaning of having a wall or fence of civilization.
That which is behind the fence is law-abiding and orderly. That which is outside is chaotic and wild. It's linked to the human world by the Bifrost rainbow bridge.
By the way, it's pronounced BIFF-roast.