The Collaborative International Dictionary of English v.0.48:

Steamboat \Steam"boat`\ (-b[=o]t`), n.
   A boat or vessel propelled by steam power; -- generally used
   of river or coasting craft, as distinguished from ocean
   steamers.
   [1913 Webster]

WordNet (r) 3.0 (2006):

steamboat
    n 1: a boat propelled by a steam engine

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "steamboat":
   boat, canoe, carry sail, circumnavigate, coast, cross, cruise,
   go by ship, go on shipboard, go to sea, make a passage, motorboat,
   navigate, ply, row, run, sail, sail round, sail the sea, scull,
   seafare, steam, steamer, steamship, take a voyage, traverse,
   voyage, yacht



U.S. Gazetteer Places (2000):

Steamboat, AZ -- U.S. Census Designated Place in Arizona
   Population (2000):    233
   Housing Units (2000): 92
   Land area (2000):     2.359399 sq. miles (6.110815 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    2.359399 sq. miles (6.110815 sq. km)
   FIPS code:            69585
   Located within:       Arizona (AZ), FIPS 04
   Location:             35.747080 N, 109.855083 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Steamboat, AZ
    Steamboat