The Collaborative International Dictionary of English v.0.48:

Natchez \Natch"ez\, n. pl. (Ethnol.)
   A tribe of Indians who formerly lived near the site of the
   city of Natchez, Mississippi. In 1729 they were subdued by
   the French; the survivors joined the Creek Confederacy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Natchez
    n 1: a town in southwest Mississippi on the Mississippi River