WordNet (r) 3.0 (2006):

outskirts
    n 1: outlying areas (as of a city or town); "they lived on the
         outskirts of Houston"; "they mingled in the outskirts of
         the crowd"

Moby Thesaurus II by Grady Ward, 1.0:

154 Moby Thesaurus words for "outskirts":
   Berlin wall, Bowery, China, Chinatown, Darkest Africa, East End,
   East Side, God knows where, Greenland, Little Hungary,
   Little Italy, North Pole, Outer Mongolia, Pago Pago,
   Pillars of Hercules, Siberia, South Pole, Stadt, Thule,
   Tierra del Fuego, Timbuktu, Ultima Thule, West End, West Side,
   Yukon, alentours, ambience, ambit, antipodes, bamboo curtain,
   banlieue, barrio, black ghetto, blighted area, boom town, border,
   border ground, borderland, borderlands, borders, borough,
   boundaries, bounds, bourg, bourns, burg, burgh, business district,
   central city, circle, circuit, circumambiencies, circumference,
   circumjacencies, circumscription, circumstances, city, city center,
   compass, confines, context, conurbation, coordinates, core,
   downtown, edge, edges, entourage, environing circumstances,
   environment, environs, exurb, exurbia, exurbs, faubourg, fringes,
   frontier, frontier post, gestalt, ghetto, ghost town,
   godforsaken place, greater city, greenbelt, habitat, inner city,
   iron curtain, jumping-off place, limitations, limits, march,
   marches, marchland, market town, megalopolis, metes,
   metes and bounds, metropolis, metropolitan area, midtown, milieu,
   municipality, neighborhood, nowhere, outback, outer space,
   outlines, outpost, outposts, pale, parameters, perimeter,
   periphery, pole, polis, precincts, purlieus, red-light district,
   residential district, run-down neighborhood, shopping center,
   situation, skid road, skid row, skirts, slum, slums, spread city,
   suburb, suburbia, suburbs, surroundings, tenderloin,
   tenement district, the Great Divide, the South Seas, the boondocks,
   the moon, the sticks, the tullies, three-mile limit,
   total environment, town, township, twelve-mile limit, uptown,
   urban blight, urban complex, urban sprawl, urbs, verges, vicinage,
   vicinity, ville