Quiz: Remember the definition of mal de mer?
c.1300, lurken "to hide, lie hidden," probably from Scandinavian (cf. dialectal Norwegian lurka "to sneak away," dialectal Swedish lurka "to be slow in one's work"), perhaps ultimately related to Middle English luren "to frown, lurk" (see lower (v.2)). Related: Lurked; 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.