The Collaborative International Dictionary of English v.0.48:

Caribou \Car"i*bou\ (k[a^]r"[i^]*b[=oo]), n. [Canadian French.]
   (Zool.)
   The American reindeer, especially the common or woodland
   species (Rangifer Caribou).
   [1913 Webster]

   Barren Ground caribou. See under Barren.

   Woodland caribou, the common reindeer (Rangifer Caribou)
      of the northern forests of America.
      [1913 Webster]

WordNet (r) 3.0 (2006):

caribou
    n 1: Arctic deer with large antlers in both sexes; called
         `reindeer' in Eurasia and `caribou' in North America [syn:
         caribou, reindeer, Greenland caribou, Rangifer
         tarandus]

U.S. Gazetteer Counties (2000):

Caribou -- U.S. County in Idaho
   Population (2000):    7304
   Housing Units (2000): 3188
   Land area (2000):     1766.011350 sq. miles (4573.948205 sq. km)
   Water area (2000):    32.612699 sq. miles (84.466498 sq. km)
   Total area (2000):    1798.624049 sq. miles (4658.414703 sq. km)
   Located within:       Idaho (ID), FIPS 16
   Location:             42.726467 N, 111.662032 W
   Headwords:
    Caribou
    Caribou, ID
    Caribou County
    Caribou County, ID


U.S. Gazetteer Places (2000):

Caribou, CA -- U.S. Census Designated Place in California
   Population (2000):    0
   Housing Units (2000): 2
   Land area (2000):     0.169139 sq. miles (0.438068 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.169139 sq. miles (0.438068 sq. km)
   FIPS code:            11166
   Located within:       California (CA), FIPS 06
   Location:             40.079929 N, 121.157397 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Caribou, CA
    Caribou


U.S. Gazetteer Places (2000):

Caribou, ME -- U.S. city in Maine
   Population (2000):    8312
   Housing Units (2000): 3858
   Land area (2000):     79.291462 sq. miles (205.363935 sq. km)
   Water area (2000):    0.887315 sq. miles (2.298135 sq. km)
   Total area (2000):    80.178777 sq. miles (207.662070 sq. km)
   FIPS code:            10565
   Located within:       Maine (ME), FIPS 23
   Location:             46.863559 N, 67.997992 W
   ZIP Codes (1990):     04736
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Caribou, ME
    Caribou