The Collaborative International Dictionary of English v.0.48:

Cestidae \Cestidae\ n.
   A family of invertebrates coextensive with the order
   Cestida; ctenophores having a greatly flattened and
   elongated body.

   Syn: family Cestidae.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Cestidae
    n 1: coextensive with the order Cestida; ctenophores having a
         greatly flattened and elongated body [syn: Cestidae,
         family Cestidae]