Source : Webster's Revised Unabridged Dictionary (1913)

Lurker \Lurk"er\, n.
   1. One who lurks.

   2. A small fishing boat. [Prov. Eng.]

Source : WordNet®

lurker
     n : someone waiting in concealment [syn: {skulker}, {lurcher}]

Source : Free On-Line Dictionary of Computing

lurker
     
        {lurking}