The Collaborative International Dictionary of English v.0.48:

Township \Town"ship\, n.
   1. The district or territory of a town.
      [1913 Webster]

   Note: In the United States, many of the States are divided
         into townships of five, six, seven, or perhaps ten
         miles square, and the inhabitants of such townships are
         invested with certain powers for regulating their own
         affairs, such as repairing roads and providing for the
         poor. The township is subordinate to the county.
         [1913 Webster]

   2. In surveys of the public land of the United States, a
      division of territory six miles square, containing 36
      sections.
      [1913 Webster]

   3. In Canada, one of the subdivisions of a county.
      [1913 Webster]

WordNet (r) 3.0 (2006):

township
    n 1: an administrative division of a county; "the town is
         responsible for snow removal" [syn: township, town]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "township":
   Kreis, Stadt, archbishopric, archdiocese, arrondissement,
   bailiwick, banlieue, bishopric, boom town, borough, bourg, burg,
   burgh, canton, city, commune, congressional district,
   constablewick, conurbation, county, departement, diocese, district,
   duchy, electoral district, electorate, exurb, exurbia, faubourg,
   ghost town, government, greater city, hamlet, hundred, magistracy,
   market town, megalopolis, metropolis, metropolitan area,
   municipality, oblast, okrug, outskirts, parish, polis, precinct,
   principality, province, region, riding, sheriffalty, sheriffwick,
   shire, shrievalty, soke, spread city, stake, state, suburb,
   suburbia, territory, town, urban complex, urban sprawl, urbs,
   village, ville, wapentake, ward