The Collaborative International Dictionary of English v.0.48:

Suburb \Sub"urb\, n. [L. suburbium; sub under, below, near +
   urbs a city. See Urban.]
   1. An outlying part of a city or town; a smaller place
      immediately adjacent to a city; in the plural, the region
      which is on the confines of any city or large town; as, a
      house stands in the suburbs; a garden situated in the
      suburbs of Paris. "In the suburbs of a town." --Chaucer.
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            [London] could hardly have contained less than
            thirty or forty thousand souls within its walls; and
            the suburbs were very populous.       --Hallam.
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   2. Hence, the confines; the outer part; the environment. "The
      suburbs . . . of sorrow." --Jer. Taylor.
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            The suburb of their straw-built citadel. --Milton.
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   Suburb roister, a rowdy; a loafer. [Obs.] --Milton.
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WordNet (r) 3.0 (2006):

suburb
    n 1: a residential district located on the outskirts of a city
         [syn: suburb, suburbia, suburban area]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "suburb":
   Stadt, banlieue, boom town, borough, bourg, burg, burgh, city,
   conurbation, exurb, exurbia, faubourg, ghost town, greater city,
   market town, megalopolis, metropolis, metropolitan area,
   municipality, outskirts, polis, spread city, suburbia, town,
   township, urban complex, urban sprawl, urbs, ville