The Collaborative International Dictionary of English v.0.48:

Cabombaceae \Cabombaceae\ prop. n.
   A subfamily of plants, in some classifications considered as
   an independent family of water lilies; it comprises the
   genera Cabomba and Brasenia.

   Syn: subfamily Cabombaceae, water-shield family.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Cabombaceae
    n 1: in some classifications considered an independent family of
         water lilies; comprises the genera Cabomba and Brasenia
         [syn: Cabombaceae, subfamily Cabombaceae, water-shield
         family]