The Collaborative International Dictionary of English v.0.48:

Filariidae \Filariidae\ n.
   a natural family consisting of threadlike roundworms, called
   filariae.

   Syn: family Filariidae.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Filariidae
    n 1: threadlike roundworms [syn: Filariidae, family
         Filariidae]