The Collaborative International Dictionary of English v.0.48:

Witan \Wit"an\, n. pl. [AS., pl. of wita sage, councilor.]
   Lit., wise men; specif. (A.-S. Hist.), The members of the
   national, or king's, council which sat to assist the king in
   administrative and judicial matters; also, the council.
   [Webster 1913 Suppl.]