pron. one, a single person or thing; a person in general
adj. one, single

Huzrah nu, kul do od, wah aan bok lingrah vod, Ahrk fin tey, boziik fun, do fin gein! Wo lost fron wah ney dov, ahrk fin reyliik do jul, voth aan suleyk wah ronit faal krein!
Hearken now, sons of snow, to an age, long ago, and the tale, boldly told, of the one! Who was kin to both wyrm, and the races of man, with a power to rival the sun!
(Book, Songs of Skyrim)

Pruzah wundunne wah Wuth Gein.
Good travels to the old one.
(Odahviing, 0009E069)

Onikaan koraav gein miraad.
Wisdom sees the one doorway.
(Odahviing, 0004DE40)

Officially defined as the pronoun ‘one’ (‘one must be careful’, ‘the one who will save us’), but also used in dialogue as the number ‘one’. Usage as a number should generally be avoided. Possibly from German ein or eins, meaning the number ‘one’.