The Collaborative International Dictionary of English v.0.48:

Octocerata \Oc`to*cer"a*ta\, n. pl. [NL., fr. Gr. 'oktw` eight +
   ?, a horn.] (Zool.)
   A suborder of Cephalopoda including Octopus, Argonauta,
   and allied genera, having eight arms around the head; --
   called also Octopoda.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Octopoda \Oc*top"o*da\, n. pl. [NL.] (Zool.)
   (a) Same as Octocerata.
   (b) Same as Arachnida.
       [1913 Webster]

WordNet (r) 3.0 (2006):

Octopoda
    n 1: octopuses and paper nautilus [syn: Octopoda, order
         Octopoda]