The Collaborative International Dictionary of English v.0.48:

Cestoda \Ces*tod"a\ (s[e^]s*t[=o]d"[.a]), prop. n. [NL., gr. Gr.
   kesto`s girdle + -oid.] (Zool.)
   A subclass of parasitic worms of the class Cestoidea. In some
   classifications, it is not differentiated from the parent
   class.
   [PJC]

WordNet (r) 3.0 (2006):

Cestoda
    n 1: tapeworms [syn: Cestoda, class Cestoda]