WordNet (r) 3.0 (2006):

confines
    n 1: a bounded scope; "he stayed within the confines of the
         city"

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "confines":
   airspace, approach, approximation, area, belt, boundaries, bounds,
   bourns, circumference, circumscription, closeness, compass,
   continental shelf, convergence, coordinates, corridor, country,
   department, district, division, edges, environs, foreground,
   fringes, ground, heartland, hinterland, immediacy,
   immediate foreground, land, limitations, limits, marches, metes,
   metes and bounds, milieu, nearness, neighborhood, nighness,
   offshore rights, outlines, outskirts, pale, parameters, part,
   parts, perimeter, periphery, place, precinct, precincts, premises,
   propinquity, proximity, purlieus, quarter, region, salient,
   section, skirts, soil, space, terrain, territory, three-mile limit,
   twelve-mile limit, verges, vicinage, vicinity, zone