The Collaborative International Dictionary of English v.0.48:

Mustang \Mus"tang\, n. [Sp. muste[~n]o belonging to the
   graziers, strayed, wild.] (Zool.)
   The half-wild horse of the plains in Mexico, California, etc.
   It is small, hardy, and easily sustained.
   [1913 Webster]

   Mustard grape (Bot.), a species of grape (Vitis
      candicans), native in Arkansas and Texas. The berries are
      small, light-colored, with an acid skin and a sweet pulp.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mustang
    n 1: small hardy range horse of the western plains descended
         from horses brought by the Spanish

The Devil's Dictionary (1881-1906):

MUSTANG, n.  An indocile horse of the western plains.  In English
society, the American wife of an English nobleman.


U.S. Gazetteer Places (2000):

Mustang, OK -- U.S. city in Oklahoma
   Population (2000):    13156
   Housing Units (2000): 4930
   Land area (2000):     12.005253 sq. miles (31.093462 sq. km)
   Water area (2000):    0.027923 sq. miles (0.072321 sq. km)
   Total area (2000):    12.033176 sq. miles (31.165783 sq. km)
   FIPS code:            50100
   Located within:       Oklahoma (OK), FIPS 40
   Location:             35.392644 N, 97.722905 W
   ZIP Codes (1990):     73064
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Mustang, OK
    Mustang


U.S. Gazetteer Places (2000):

Mustang, TX -- U.S. town in Texas
   Population (2000):    47
   Housing Units (2000): 23
   Land area (2000):     0.126140 sq. miles (0.326700 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.126140 sq. miles (0.326700 sq. km)
   FIPS code:            50184
   Located within:       Texas (TX), FIPS 48
   Location:             32.012629 N, 96.431178 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Mustang, TX
    Mustang