n. Mundus, the world; world

Alduin, feyn do jun, kruziik vokun staadnau, voth aan bahlok wah diivon fin lein!
Alduin, Bane of Kings, ancient shadow unbound, with a hunger to swallow the world!
(Book, Songs of Skyrim)

Grik los lein.
Such is the world.
(Paarthurnax, 0009C20C)

Daar Lein los dii.
This world is mine.
(Alduin, 000ED35F)

Zu'u Alduin, zok sahrot do naan ko Lein.
I (am still) Alduin, most mighty of any in Mundus (the world).
(Alduin, 000ED362)

Sometime used as a proper noun; Lein means “the World” in and by itself. The definite article fin is only used for metric reasons in the Song of the Dragonborn.