Source : Webster's Revised Unabridged Dictionary (1913)

Sneaky \Sneak"y\, n.
   Like a sneak; sneaking.

Source : WordNet®

sneaky
     adj 1: marked by deception; "achieved success in business only by
            underhand methods" [syn: {underhand}, {underhanded}]
     2: marked by quiet and caution and secrecy; taking pains to
        avoid being observed; "a furtive manner"; "a lurking
        prowler"; "a sneak attack"; "stealthy footsteps"; "a
        surreptitious glance at his watch"; "someone skulking in
        the shadows" [syn: {furtive}, {lurking}, {skulking}, {sneak(a)},
         {stealthy}, {surreptitious}]