The Collaborative International Dictionary of English v.0.48:

Octopus \Oc"to*pus\, n. [NL. See Octopod.]
   1. (Zool.) A genus of eight-armed cephalopods, including
      numerous species, some of them of large size. See
      Devilfish.
      [1913 Webster]

   2. (Zool.) Any member of the genus Octopus.
      [PJC]

   3. (Fig.) Something resembling an octopus in having numerous
      controlling arms or branches that reach widely and
      influence many activities; -- used mostly of
      organizations, such as diversified corporations.
      [PJC]

WordNet (r) 3.0 (2006):

octopus
    n 1: tentacles of octopus prepared as food
    2: bottom-living cephalopod having a soft oval body with eight
       long tentacles [syn: octopus, devilfish]