Yggdrasil (Old Norse Yggdrasill — "Ygg's (Odin's) horse" or "the terrible steed") is the World Tree of Scandinavian cosmology, a giant ash, connecting all Nine Worlds.

The Nine Worlds of Yggdrasil

• Asgard (Ásgarðr) — the world of the Aesir (Odin, Thor, Freya)
• Vanaheim (Vanaheimr) — the world of the Vanir (Njord, Freyr)
• Alfheim (Álfheimr) — the world of the light elves
• Midgard (Miðgarðr) — the world of humans
• Jotunheim (Jötunheimr) — the world of giants
• Svartalfheim (Svartálfaheimr) — the world of dark elves / dwarves
• Niflheim (Niflheimr) — the world of primordial ice
• Muspellheim (Múspellsheimr) — the world of primordial fire
• Hel — the world of the dead

Three Wells at the Roots

The Well of Urd (Urðarbrunnr) — where the three Norns dwell, spinning the Wyrd (T025).

Mimir's Well (Mímisbrunnr) — the source of wisdom, in which Odin sacrificed an eye for knowledge.

Hvergelmir — the source of all rivers of the universe.

Yggdrasil in Errarium

The cosmological frame of the runes. In the Errarium context, Yggdrasil is the cosmological frame within which the runes (T068) operate: each rune is an aspect of the forces acting through the Tree.

Comparison with the Tree of Sephirot. The structural analog is the Tree of Sephirot in Kabbalah (#17), but with a fundamentally different cosmology: for the Norse it is an organic tree of worlds, for the Kabbalists it is a scheme of emanation.