3. Of or pertaining to shade or darkness; hence, unfit to be seen or known; equivocal; dubious or corrupt. A shady business. 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. To keep shady, to stay in concealment; also, to be reticent.
Origin: Shadier; Shadiest.