The Collaborative International Dictionary of English v.0.48:

Ziphiidae \Zi*phi"i*dae\, prop. n.
   A natural family of cetaceans comprising the beaked whales;
   in some esp. former classifications included in the family
   Physeteridae.

   Syn: family Ziphiidae, Hyperodontidae, family
        Hyperodontidae.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Ziphiidae
    n 1: beaked whales; in some especially former classifications
         included in the family Physeteridae [syn: Ziphiidae,
         family Ziphiidae, Hyperodontidae, family
         Hyperodontidae]