The Collaborative International Dictionary of English v.0.48:

Cisco \Cis"co\, n. (Zool.)
   The Lake herring (Coregonus Artedi), valuable food fish of
   the Great Lakes of North America. The name is also applied to
   Coregonus Hoyi, a related species of Lake Michigan.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cisco
    n 1: cold-water fish caught in Lake Superior and northward [syn:
         lake herring, cisco]
    2: important food fish of cold deep lakes of North America [syn:
       cisco, lake herring, Coregonus artedi]

U.S. Gazetteer Places (2000):

Cisco, NE -- U.S. Census Designated Place in Nebraska
   Population (2000):    68
   Housing Units (2000): 45
   Land area (2000):     0.575741 sq. miles (1.491161 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.575741 sq. miles (1.491161 sq. km)
   FIPS code:            09112
   Located within:       Nebraska (NE), FIPS 31
   Location:             41.498324 N, 102.622124 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Cisco, NE
    Cisco


U.S. Gazetteer Places (2000):

Cisco, IL -- U.S. village in Illinois
   Population (2000):    264
   Housing Units (2000): 113
   Land area (2000):     0.381133 sq. miles (0.987131 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.381133 sq. miles (0.987131 sq. km)
   FIPS code:            14442
   Located within:       Illinois (IL), FIPS 17
   Location:             40.011799 N, 88.725764 W
   ZIP Codes (1990):     61830
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Cisco, IL
    Cisco


U.S. Gazetteer Places (2000):

Cisco, TX -- U.S. city in Texas
   Population (2000):    3851
   Housing Units (2000): 1849
   Land area (2000):     4.849369 sq. miles (12.559807 sq. km)
   Water area (2000):    0.008135 sq. miles (0.021070 sq. km)
   Total area (2000):    4.857504 sq. miles (12.580877 sq. km)
   FIPS code:            15004
   Located within:       Texas (TX), FIPS 48
   Location:             32.384762 N, 98.981265 W
   ZIP Codes (1990):     76437
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Cisco, TX
    Cisco