The Collaborative International Dictionary of English v.0.48:

Noisome \Noi"some\, a. [For noysome, fr. noy for annoy. See
   Annoy.]
   1. Noxious to health; hurtful; mischievous; unwholesome;
      insalubrious; destructive; as, noisome effluvia. "Noisome
      pestilence." --Ps. xci. 3.
      [1913 Webster]

   2. Offensive to the smell or other senses; disgusting; fetid.
      "Foul breath is noisome." --Shak.
      [1913 Webster] -- Noi"some*ly, adv. -- Noi"some*ness,
      n.
      [1913 Webster]

   Syn: Noxious; unwholesome; insalubrious; mischievous;
        destructive.

   Usage: Noisome, Noxious. These words have to a great
          extent been interchanged; but there is a tendency to
          make a distinction between them, applying noxious to
          things that inflict evil directly; as, a noxious
          plant, noxious practices, etc., and noisome to things
          that operate with a remoter influence; as, noisome
          vapors, a noisome pestilence, etc. Noisome has the
          additional sense of disqusting. A garden may be free
          from noxious weeds or animals; but, if recently
          covered with manure, it may be filled with a noisome
          smell.
          [1913 Webster]

WordNet (r) 3.0 (2006):

noisome
    adj 1: causing or able to cause nausea; "a nauseating smell";
           "nauseous offal"; "a sickening stench" [syn:
           nauseating, nauseous, noisome, queasy,
           loathsome, offensive, sickening, vile]
    2: offensively malodorous; "a foul odor"; "the kitchen smelled
       really funky" [syn: fetid, foetid, foul, foul-
       smelling, funky, noisome, smelly, stinking, ill-
       scented]

Moby Thesaurus II by Grady Ward, 1.0:

186 Moby Thesaurus words for "noisome":
   abhorrent, abominable, arrant, atrocious, awful, bad, bad for,
   bad-smelling, baleful, baneful, barfy, base, beastly,
   below contempt, beneath contempt, blameworthy, brackish, brutal,
   cloying, contaminated, contemptible, corroding, corrosive,
   corrupting, corruptive, counterproductive, crude, damaging, deadly,
   deleterious, deplorable, despicable, detestable, detrimental, dire,
   dirty, disadvantageous, disgusting, disserviceable, distressing,
   dreadful, egregious, enormous, execrable, fecal, fetid, filthy,
   flagrant, forbidding, foul, frowsty, frowy, frowzy, fulsome, funky,
   fusty, gamy, graveolent, grievous, gross, harmful, hateful,
   heinous, high, horrible, horrid, hurtful, icky, ignoble,
   ill-smelling, infamous, injurious, insalubrious, insanitary,
   lamentable, lethal, loathsome, lousy, maggoty, malefic, malevolent,
   malign, malignant, malodorous, mawkish, mephitic, miasmal, miasmic,
   mildewed, mildewy, mischievous, moldy, monstrous, morbific, musty,
   nasty, nauseant, nauseating, nauseous, nefarious, nidorous,
   notorious, noxious, objectionable, obnoxious, obscene, odious,
   odorous, offensive, olid, ominous, outrageous, overripe,
   pathogenic, peccant, pernicious, pestiferous, pitiable, pitiful,
   poisonous, polluted, prejudicial, putrid, rancid, rank, reasty,
   reasy, rebarbative, reechy, reeking, reeky, regrettable, repellent,
   reprehensible, repugnant, repulsive, revolting, rotten, sad,
   scandalous, scatheful, schlock, scurvy, septic, shabby, shameful,
   shocking, shoddy, sickening, sickly, smellful, smelling, smelly,
   sordid, spoiled, squalid, stenchy, stinking, strong, stuffy,
   sulfurous, tainted, terrible, too bad, toxic, unclean, unhealthful,
   unhealthy, unhygienic, unsanitary, unwholesome, venenate,
   veneniferous, venenous, venomous, vicious, vile, villainous,
   virulent, vomity, weevily, woeful, worst, worthless, wretched,
   yucky