Source : Webster's Revised Unabridged Dictionary (1913)

Santees \San`tees"\, n. pl.; sing. {Santee}. (Ethnol.)
   One of the seven confederated tribes of Indians belonging to
   the Sioux, or Dakotas.

Source : WordNet®

Santee
     n 1: a member of the eastern branch of the Sioux [syn: {Santee
          Sioux}, {Santee Dakota}, {Eastern Sioux}]
     2: the Siouan language spoken by the Santee people