The Collaborative International Dictionary of English v.0.48:

niagara \niagara\ n.

   Note: lower case [from the famous water falls.]
   A large flow, used figuratively.

   Syn: cascade.
        [PJC] Niagara

The Collaborative International Dictionary of English v.0.48:

Niagara \Niagara\, Niagara Falls \Niagara Falls\prop. n.
   A large waterfall on the Niagara River near Buffalo
   remarkable for the volume and constancy of the water flowing
   over it. That part of the waterfall in Canada is the
   Horseshoe Falls; the U. S. portion is called the American
   Falls.
   [WordNet 1.5] Niagara

The Collaborative International Dictionary of English v.0.48:

Niagara \Niagara\, Niagara River \Niagara River\prop. n.
   A river flowing from Lake Erie into Lake Ontario, which forms
   the boundary between Ontario and New York.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

Niagara
    n 1: waterfall in Canada is the Horseshoe Falls; in the United
         States it is the American Falls [syn: Niagara, Niagara
         Falls]
    2: a river flowing from Lake Erie into Lake Ontario; forms
       boundary between Ontario and New York [syn: Niagara,
       Niagara River]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "Niagara":
   cascade, cataract, deluge, fall, falls, flood, force, fresh,
   freshet, linn, nappe, pour, river, sault, spate, torrent,
   waterfall, waterflood, watershoot



U.S. Gazetteer Counties (2000):

Niagara -- U.S. County in New York
   Population (2000):    219846
   Housing Units (2000): 95715
   Land area (2000):     522.947653 sq. miles (1354.428146 sq. km)
   Water area (2000):    616.885584 sq. miles (1597.726259 sq. km)
   Total area (2000):    1139.833237 sq. miles (2952.154405 sq. km)
   Located within:       New York (NY), FIPS 36
   Location:             43.146089 N, 78.848097 W
   Headwords:
    Niagara
    Niagara, NY
    Niagara County
    Niagara County, NY


U.S. Gazetteer Places (2000):

Niagara, WI -- U.S. city in Wisconsin
   Population (2000):    1880
   Housing Units (2000): 812
   Land area (2000):     2.740240 sq. miles (7.097190 sq. km)
   Water area (2000):    0.269695 sq. miles (0.698508 sq. km)
   Total area (2000):    3.009935 sq. miles (7.795698 sq. km)
   FIPS code:            57325
   Located within:       Wisconsin (WI), FIPS 55
   Location:             45.778244 N, 88.003867 W
   ZIP Codes (1990):     54151
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Niagara, WI
    Niagara


U.S. Gazetteer Places (2000):

Niagara, ND -- U.S. city in North Dakota
   Population (2000):    57
   Housing Units (2000): 35
   Land area (2000):     0.931686 sq. miles (2.413055 sq. km)
   Water area (2000):    0.026700 sq. miles (0.069152 sq. km)
   Total area (2000):    0.958386 sq. miles (2.482207 sq. km)
   FIPS code:            56780
   Located within:       North Dakota (ND), FIPS 38
   Location:             47.997001 N, 97.869353 W
   ZIP Codes (1990):     58266
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Niagara, ND
    Niagara