WordNet (r) 3.0 (2006):

dystopia
    n 1: state in which the conditions of life are extremely bad as
         from deprivation or oppression or terror [ant: utopia]
    2: a work of fiction describing an imaginary place where life is
       extremely bad because of deprivation or oppression or terror

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "dystopia":
   Agapemone, Arcadia, Big Rock-Candy Mountain, Canaan,
   Cloudcuckooland, Cockaigne, Eden, Eldorado, Erewhon,
   Garden of Eden, Goshen, Happy Valley, Land of Youth, Laputa,
   Never-Never-land, Neverland, New Atlantis, Pandemonium, Quivira,
   Shangri-la, Utopia, cloudland, dreamland, faerie, fairyland,
   heaven, kakotopia, kingdom come, land of dreams,
   land of enchantment, land of faerie, land of plenty,
   land of promise, lotus land, millennium, paradise, promised land,
   utopia, wonderland