The Collaborative International Dictionary of English v.0.48:

Blackfoot \Black"foot`\, a.
   Of or pertaining to the Blackfeet; as, a Blackfoot Indian. --
   n. A Blackfoot Indian.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Blackfoot
    n 1: a member of a warlike group of Algonquians living in the
         northwestern plains
    2: any of the Algonquian languages spoken by the Blackfoot

U.S. Gazetteer Places (2000):

Blackfoot, ID -- U.S. city in Idaho
   Population (2000):    10419
   Housing Units (2000): 3929
   Land area (2000):     5.408660 sq. miles (14.008364 sq. km)
   Water area (2000):    0.255463 sq. miles (0.661647 sq. km)
   Total area (2000):    5.664123 sq. miles (14.670011 sq. km)
   FIPS code:            07840
   Located within:       Idaho (ID), FIPS 16
   Location:             43.190068 N, 112.346037 W
   ZIP Codes (1990):     83221
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Blackfoot, ID
    Blackfoot