Source : Webster's Revised Unabridged Dictionary (1913)

Lurk \Lurk\, v. i. [imp. & p. p. {Lurked}; p. pr. & vb. n.
   {Lurking}.] [OE. lurken, lorken, prob. a dim. from the source
   of E. lower to frown. See {Lower}, and cf. {Lurch}, a sudden
   roll, {Lurch} to lurk.]
   1. To lie hid; to lie in wait.

            Like wild beasts, lurking in loathsome den.
                                                  --Spenser.

            Let us . . . lurk privily for the innocent. --Prov.
                                                  i. 11.

   2. To keep out of sight.

            The defendant lurks and wanders about in Berks.
                                                  --Blackstone.

Source : WordNet®

lurking
     adj 1: concealed and unsuspected; "lurking dangers"; "search for
            lurking ambiguities"
     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}, {skulking}, {sneak(a)}, {sneaky},
         {stealthy}, {surreptitious}]

Source : Free On-Line Dictionary of Computing

lurking
     
         The activity of one of the "silent
        majority" in a electronic forum such as {Usenet}; posting
        occasionally or not at all but reading the group's postings
        regularly.  This term is not pejorative and indeed is casually
        used reflexively: "Oh, I'm just lurking".  Often used in "the
        lurkers", the hypothetical audience for the group's
        {flamage}-emitting regulars.
     
        Lurking and reading the {FAQ} are recommended {netiquette} for
        beginners who need to learn the history and practises of the
        group before posting.
     
        (1997-06-14)