[syn: shady, shadowed, shadowy, umbrageous]
The Collaborative International Dictionary of English v.0.48:
Shady \Shad"y\, a. [Compar. Shadier; superl. Shadiest.]
   1. Abounding in shade or shades; overspread with shade;
      causing shade.
      [1913 Webster]
            The shady trees cover him with their shadow. --Job.
                                                  xl. 22.
      [1913 Webster]
            And Amaryllis fills the shady groves. --Dryden.
      [1913 Webster]
   2. Sheltered from the glare of light or sultry heat.
      [1913 Webster]
            Cast it also that you may have rooms shady for
            summer and warm for winter.           --Bacon.
      [1913 Webster]
   3. Of or pertaining to shade or darkness; hence, unfit to be
      seen or known; of questionable character; unsavory;
      equivocal; dubious, corrupt, or criminal; as, a shady
      character; -- of people or activities. [Colloq.] "A shady
      business." --London Sat. Rev.
            Shady characters, disreputable, criminal. --London
                                                  Spectator.
      [1913 Webster]
   On the shady side of, on the thither side of; as, on the
      shady side of fifty; that is, more than fifty. [Colloq.]
   To keep shady, to stay in concealment; also, to be
      reticent. [Slang]
      [1913 Webster]
WordNet (r) 3.0 (2006):
shady
    adj 1: (of businesses and businessmen) unscrupulous; "a shady
           operation" [syn: fly-by-night, shady]
    2: of questionable taste or morality; "a louche nightclub"; "a
       louche painting" [syn: louche, shady]
    3: not as expected; "there was something fishy about the
       accident"; "up to some funny business"; "some definitely
       queer goings-on"; "a shady deal"; "her motives were suspect";
       "suspicious behavior" [syn: fishy, funny, shady,
       suspect, suspicious]
    4: filled with shade; "the shady side of the street"; "the
       surface of the pond is dark and shadowed"; "we sat on rocks
       in a shadowy cove"; "cool umbrageous woodlands" [syn:
       shady, shadowed, shadowy, umbrageous]
Moby Thesaurus II by Grady Ward, 1.0:
93 Moby Thesaurus words for "shady":
   amoral, bent, blue, bosky, broad, clouded, conscienceless, corrupt,
   corrupted, criminal, crooked, curtained, dark, darkling,
   derogatory, devious, discreditable, disgraceful, dishonest,
   dishonorable, disreputable, doubtful, dubious, dusky, equivocal,
   evasive, felonious, fishy, fraudulent, ignoble, ignominious,
   ill-got, ill-gotten, immoral, indecisive, indefinite, indirect,
   indistinct, infamous, inglorious, insidious, not kosher, notorious,
   obumbrate, obumbrated, off-color, overshaded, overshadowed,
   penumbral, purple, questionable, racy, rotten, salty, screened,
   seamy, shabby, shaded, shadow, shadowy, shameful, shameless,
   sheltered, shifty, shoddy, sinister, slippery, sordid, spicy,
   suggestive, suspect, suspicious, tricky, umbral, uncertain,
   unconscienced, unconscientious, unconscionable, undecided,
   underhand, underhanded, unethical, unpraiseworthy, unprincipled,
   unreliable, unrespectable, unsavory, unscrupulous,
   unstraightforward, veiled, wicked, without remorse,
   without shame