The Collaborative International Dictionary of English v.0.48:
Santees \San`tees"\, n. pl.; sing. Santee. (Ethnol.) One of the seven confederated tribes of Indians belonging to the Sioux, or Dakotas. [1913 Webster]WordNet (r) 3.0 (2006):
Santee n 1: a member of the eastern branch of the Sioux [syn: Santee, Santee Sioux, Santee Dakota, Eastern Sioux] 2: the Siouan language spoken by the Santee