The Collaborative International Dictionary of English v.0.48:

Osages \O*sa"ges\, n. pl.; sing. Osage. (Ethnol.)
   A tribe of southern Sioux Indians, now living in the Indian
   Territory.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Osage \Osage\ prop. n.
   A tributary of the Missouri River.

   Syn: Osage River.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Osage \Osage\ prop. n.
   1. A member of the Osages, a tribe of North American Indians
      formerly living in western Missouri.
      [PJC]

   2. The language of the Osages, a siouxan language.
      [PJC]

WordNet (r) 3.0 (2006):

Osage
    n 1: a member of the Siouan people formerly living in Missouri
         in the valleys of the Missouri and Osage rivers; oil was
         found on Osage lands early in the 20th century
    2: a river in Missouri that is a tributary of the Missouri River
       [syn: Osage, Osage River]
    3: the Dhegiha dialect spoken by the Osage