worm

worm n.  [from `tapeworm' in John Brunner's novel
   "The Shockwave Rider", via XEROX PARC] A program that
   propagates itself over a network, reproducing itself as it goes.
   Compare {virus}.  Nowadays the term has negative connotations,
   as it is assumed that only {cracker}s write worms.  Perhaps the
   best-known example was Robert T. Morris's `Internet Worm' of 1988,
   a `benign' one that got out of control and hogged hundreds of
   Suns and VAXen across the U.S.  See also {cracker}, {RTM},
   {Trojan horse}, {ice}, and {Great Worm, the}.