The Collaborative International Dictionary of English v.0.48:

Sordid \Sor"did\, a. [L. sordidus, fr. sordere to be filthy or
   dirty; probably akin to E. swart: cf. F. sordide. See
   Swart, a.]
   1. Filthy; foul; dirty. [Obs.]
      [1913 Webster]

            A sordid god; down from his hoary chin
            A length of beard descends, uncombed, unclean.
                                                  --Dryden.
      [1913 Webster]

   2. Vile; base; gross; mean; as, vulgar, sordid mortals. "To
      scorn the sordid world." --Milton.
      [1913 Webster]

   3. Meanly avaricious; covetous; niggardly.
      [1913 Webster]

            He may be old,
            And yet sordid, who refuses gold.     --Sir J.
                                                  Denham.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sordid
    adj 1: morally degraded; "a seedy district"; "the seamy side of
           life"; "sleazy characters hanging around casinos";
           "sleazy storefronts with...dirt on the walls"- Seattle
           Weekly; "the sordid details of his orgies stank under his
           very nostrils"- James Joyce; "the squalid atmosphere of
           intrigue and betrayal" [syn: seamy, seedy, sleazy,
           sordid, squalid]
    2: unethical or dishonest; "dirty police officers"; "a sordid
       political campaign" [syn: dirty, sordid]
    3: foul and run-down and repulsive; "a flyblown bar on the edge
       of town"; "a squalid overcrowded apartment in the poorest
       part of town"; "squalid living conditions"; "sordid
       shantytowns" [syn: flyblown, squalid, sordid]
    4: meanly avaricious and mercenary; "sordid avarice"; "sordid
       material interests"

Moby Thesaurus II by Grady Ward, 1.0:

206 Moby Thesaurus words for "sordid":
   a hog for, abased, abominable, acquisitive, all-devouring, arrant,
   atrocious, avaricious, avid, awful, base, beastly, beat-up,
   bedraggled, beneath contempt, black, blameworthy, blowsy, blowzy,
   bottomless, brutal, careless, chintzy, contemptible, corrupt,
   coveting, covetous, debased, defiled, degraded, deplorable,
   derogatory, despicable, deteriorated, detestable, devouring,
   dilapidated, dingy, dire, dirty, discreditable, disgusting,
   dishonorable, disreputable, dowdy, down-and-out, drabbletailed,
   draggled, draggletailed, dreadful, egregious, enormous, esurient,
   execrable, feculent, fetid, filthy, flagrant, foul, frowsy, frowzy,
   frumpish, frumpy, fulsome, gluttonous, gobbling, grabby, grasping,
   greedy, grievous, gross, grubby, grudging, hateful, heinous,
   hoggish, horrible, horrid, ignoble, ignominious, impoverished,
   impure, in rags, infamous, informal, inglorious, insanitary,
   insatiable, insatiate, lamentable, limitless, loathsome, loose,
   lousy, low, low-down, lumpen, maggoty, mean, mercenary, messy,
   mingy, miserable, miserly, money-hungry, money-mad, monstrous,
   mucky, mussy, nasty, nefarious, negligent, niggard, niggardly,
   noisome, notorious, obnoxious, odious, offensive, omnivorous,
   outrageous, overgreedy, parsimonious, penurious, piggish,
   pinchpenny, pitiable, pitiful, poky, polluted, poor,
   poverty-stricken, putrid, quenchless, ragged, raggedy, ramshackle,
   rank, rapacious, ravening, ravenous, regrettable, reprehensible,
   repulsive, rotten, ruinous, sad, scandalous, schlock, scraggly,
   scurvy, seamy, seedy, selfish, servile, shabby, shady, shameful,
   shocking, shoddy, slack, slakeless, slattern, slatternly, sleazy,
   slimy, slipshod, sloppy, slovenly, slumlike, slummy, sluttish,
   sodden, squalid, stingy, swinish, tacky, tattered, terrible,
   too bad, tumbledown, unappeasable, unappeased, unclean, uncleanly,
   unkempt, unneat, unpraiseworthy, unquenchable, unrespectable,
   unsanitary, unsated, unsatisfied, unsavory, unsightly, unslakeable,
   unslaked, untidy, venal, vile, villainous, voracious, woeful,
   worst, worthless, wretched