The Collaborative International Dictionary of English v.0.48:

Athyriaceae \Athyriaceae\ n.
   1. alternative names for one of a number of families into
      which the family Polypodiaceae has been subdivided in
      some classification systems.

   Syn: Dryopteridaceae, family Dryopteridaceae, family
        Athyriaceae.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Athyriaceae
    n 1: alternative names for one of a number of families into
         which the family Polypodiaceae has been subdivided in some
         classification systems [syn: Dryopteridaceae, family
         Dryopteridaceae, Athyriaceae, family Athyriaceae]