WordNet (r) 3.0 (2006):

Caddo
    n 1: a group of Plains Indians formerly living in what is now
         North and South Dakota and Nebraska and Kansas and Arkansas
         and Louisiana and Oklahoma and Texas
    2: a family of North American Indian languages spoken widely in
       the Midwest by the Caddo [syn: Caddo, Caddoan, Caddoan
       language]