The Collaborative International Dictionary of English v.0.48:

Wyn \Wyn\, Wynn \Wynn\, n. Also Wen \Wen\ [AS. w[=e]n.]
   One of the runes (?) adopted into the Anglo-Saxon, or Old
   English, alphabet. It had the value of modern English w, and
   was replaced from about a. d. 1280 at first by uu, later by
   w.