Source : Webster's Revised Unabridged Dictionary (1913)

Skulk \Skulk\, Skulker \Skulk"er\, n.
   One who, or that which, skulks.

Source : WordNet®

skulker
     n 1: someone shirking their duty by feigning illness or
          incapacity [syn: {malingerer}, {shammer}]
     2: someone waiting in concealment [syn: {lurker}, {lurcher}]

Source : Free On-Line Dictionary of Computing

skulker
     
        {prowler}