The Collaborative International Dictionary of English v.0.48:

Decapod \Dec"a*pod\ (d[e^]k"[.a]*p[o^]d), n. [Cf. F.
   d['e]capode.] (Zool.)
   A crustacean with ten feet or legs, as a crab; one of the
   Decapoda. Also used adjectively, as a decapod crustacean.
   [1913 Webster]

WordNet (r) 3.0 (2006):

decapod
    n 1: crustaceans characteristically having five pairs of
         locomotor appendages each joined to a segment of the thorax
         [syn: decapod crustacean, decapod]
    2: cephalopods having eight short tentacles plus two long ones