The Collaborative International Dictionary of English v.0.48:

Palmetto \Pal*met"to\, n. [Dim. of palm the tree: cf. Sp.
   palmito.] (Bot.)
   A name given to palms of several genera and species growing
   in the West Indies and the Southern United States. In the
   United States, the name is applied especially to the
   Cham[ae]rops Palmetto, or Sabal Palmetto, the cabbage
   tree of Florida and the Carolinas. See Cabbage tree, under
   Cabbage.
   [1913 Webster]

   Royal palmetto, the West Indian Sabal umbraculifera, the
      trunk of which, when hollowed, is used for water pipes,
      etc. The leaves are used for thatching, and for making
      hats, ropes, etc.

   Saw palmetto, Sabal serrulata, a native of Georgia, South
      Carolina, and Florida. The nearly impassable jungle which
      it forms is called palmetto scrub.
      [1913 Webster]

WordNet (r) 3.0 (2006):

palmetto
    n 1: any of several low-growing palms with fan-shaped leaves

U.S. Gazetteer Places (2000):

Palmetto, FL -- U.S. city in Florida
   Population (2000):    12571
   Housing Units (2000): 5776
   Land area (2000):     4.315565 sq. miles (11.177262 sq. km)
   Water area (2000):    0.134124 sq. miles (0.347379 sq. km)
   Total area (2000):    4.449689 sq. miles (11.524641 sq. km)
   FIPS code:            54250
   Located within:       Florida (FL), FIPS 12
   Location:             27.522115 N, 82.578418 W
   ZIP Codes (1990):     34221
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Palmetto, FL
    Palmetto


U.S. Gazetteer Places (2000):

Palmetto, GA -- U.S. city in Georgia
   Population (2000):    3400
   Housing Units (2000): 1283
   Land area (2000):     5.181588 sq. miles (13.420251 sq. km)
   Water area (2000):    0.102646 sq. miles (0.265853 sq. km)
   Total area (2000):    5.284234 sq. miles (13.686104 sq. km)
   FIPS code:            58884
   Located within:       Georgia (GA), FIPS 13
   Location:             33.521117 N, 84.667662 W
   ZIP Codes (1990):     30268
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Palmetto, GA
    Palmetto


U.S. Gazetteer Places (2000):

Palmetto, LA -- U.S. village in Louisiana
   Population (2000):    188
   Housing Units (2000): 94
   Land area (2000):     0.901375 sq. miles (2.334551 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.901375 sq. miles (2.334551 sq. km)
   FIPS code:            58780
   Located within:       Louisiana (LA), FIPS 22
   Location:             30.716729 N, 91.907648 W
   ZIP Codes (1990):     71358
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Palmetto, LA
    Palmetto