The Collaborative International Dictionary of English v.0.48:

Savanna \Sa*van"na\, n. [Of American Indian origin; cf. Sp.
   sabana, F. savane.]
   A tract of level land covered with the vegetable growth
   usually found in a damp soil and warm climate, -- as grass or
   reeds, -- but destitute of trees. [Spelt also savannah.]
   [1913 Webster]

         Savannahs are clear pieces of land without woods.
                                                  --Dampier.
   [1913 Webster]

   Savanna flower (Bot.), a West Indian name for several
      climbing apocyneous plants of the genus Echites.

   Savanna sparrow (Zool.), an American sparrow (Ammodramus
      sandwichensis or Passerculus savanna) of which several
      varieties are found on grassy plains from Alaska to the
      Eastern United States.

   Savanna wattle (Bot.), a name of two West Indian trees of
      the genus Citharexylum.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Savannah
    n 1: a port in eastern Georgia near the mouth of the Savannah
         river
    2: a river in South Carolina that flows southeast to the
       Atlantic [syn: Savannah, Savannah River]
    3: a flat grassland in tropical or subtropical regions [syn:
       savanna, savannah]

U.S. Gazetteer Places (2000):

Savannah, MO -- U.S. city in Missouri
   Population (2000):    4762
   Housing Units (2000): 2038
   Land area (2000):     3.126293 sq. miles (8.097062 sq. km)
   Water area (2000):    0.003460 sq. miles (0.008962 sq. km)
   Total area (2000):    3.129753 sq. miles (8.106024 sq. km)
   FIPS code:            66044
   Located within:       Missouri (MO), FIPS 29
   Location:             39.941066 N, 94.830873 W
   ZIP Codes (1990):     64485
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Savannah, MO
    Savannah


U.S. Gazetteer Places (2000):

Savannah, GA -- U.S. city in Georgia
   Population (2000):    131510
   Housing Units (2000): 57437
   Land area (2000):     74.742188 sq. miles (193.581369 sq. km)
   Water area (2000):    3.365406 sq. miles (8.716362 sq. km)
   Total area (2000):    78.107594 sq. miles (202.297731 sq. km)
   FIPS code:            69000
   Located within:       Georgia (GA), FIPS 13
   Location:             32.050706 N, 81.103762 W
   ZIP Codes (1990):     31401 31405 31406 31409 31410 31411
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Savannah, GA
    Savannah


U.S. Gazetteer Places (2000):

Savannah, OH -- U.S. village in Ohio
   Population (2000):    372
   Housing Units (2000): 147
   Land area (2000):     0.443339 sq. miles (1.148242 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.443339 sq. miles (1.148242 sq. km)
   FIPS code:            70576
   Located within:       Ohio (OH), FIPS 39
   Location:             40.965249 N, 82.365168 W
   ZIP Codes (1990):     44874
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Savannah, OH
    Savannah


U.S. Gazetteer Places (2000):

Savannah, TN -- U.S. city in Tennessee
   Population (2000):    6917
   Housing Units (2000): 3206
   Land area (2000):     5.728337 sq. miles (14.836323 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    5.728337 sq. miles (14.836323 sq. km)
   FIPS code:            66720
   Located within:       Tennessee (TN), FIPS 47
   Location:             35.223674 N, 88.237011 W
   ZIP Codes (1990):     38372
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Savannah, TN
    Savannah