Yggdrasil
/ˈɪɡdrəsɪl
/Scandinavian Mythology
A huge ash tree located at the centre of the earth, with three roots, one extending to Niflheim (the underworld), one to Jotunheim (land of the giants), and one to Asgard (land of the gods).
Origin
From Old Norse yg(g)drasill, apparently from Yggr 'Odin' + drasill 'horse'.