Source : Webster's Revised Unabridged Dictionary (1913)

Shady \Shad"y\, a. [Compar. {Shadier}; superl. {Shadiest}.]
   1. Abounding in shade or shades; overspread with shade;
      causing shade.

            The shady trees cover him with their shadow. --Job.
                                                  xl. 22.

            And Amaryllis fills the shady groves. --Dryden.

   2. Sheltered from the glare of light or sultry heat.

            Cast it also that you may have rooms shady for
            summer and warm for winter.           --Bacon.

   3. Of or pertaining to shade or darkness; hence, unfit to be
      seen or known; equivocal; dubious or corrupt. [Colloq.]
      ``A shady business.'' --London Sat. Rev.

            Shady characters, disreputable, criminal. --London
                                                  Spectator.

   {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]