The Collaborative International Dictionary of English v.0.48:

Winnebagoes \Win`ne*ba"goes\, n.; sing. Winnebago. (Ethnol.)
   A tribe of North American Indians who originally occupied the
   region about Green Bay, Lake Michigan, but were driven back
   from the lake and nearly exterminated in 1640 by the
   IIlinnois.
   [1913 Webster]