Yggdrasil [ˈyɡːˌdrasilː] is a large tree from Norse mythology that connects nine different worlds. The etymology is unknown, however, it’s generally accepted to mean Odin’s horse. Though many say it means world tree, after askr (ash) Yggrasill. We will probably never learn the truth, but it doesn’t hinder the tree’s mystery and allure.
In mythology, the massive ash tree sits at the center of the cosmos, and it’s three roots extend to three locations, while it’s branches also travel to the nine worlds. If you count them all, including our world, there are actually more than nine. Nine came to be a continuous number because Odin created the nine worlds. However, three other worlds existed prior to them.
Urðarbrunnr, Hvergelmir, and Mímisbrunnr are all associated with water. The first is the home of the Norns and lies beneath the world tree. The second is a bubbling spring from which all waters rise, and it’s located in Niflheim. The last is Mirmir’s well, the place where Odin sacrificed his eye to gain knowledge, and it’s located in a special place within Jötunheimr, called Ginnungagap– this is where the universe formed in Norse Mythology.
Trees are often sacred in religion. Ash, in turn, became sacred to the Norse as Odin himself decreed it. Some scholars believe Yggdrasil is here on Midgard, but those of the revised Norse faith believe otherwise. Either way it’s a fascinating piece of lore for writers to study in world building or the historic aspect of the Norse.