The Collaborative International Dictionary of English v.0.48:

Dicksonia \Dicksonia\ prop. n.
   A genus of tree ferns of temperate Australasia having
   bipinnatifid or tripinnatifid fronds and usually marginal
   sori; in some classification systems it is placed in the
   family Cyatheaceae.

   Syn: genus Dicksonia.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Dicksonia
    n 1: tree ferns of temperate Australasia having bipinnatifid or
         tripinnatifid fronds and usually marginal sori; in some
         classification systems placed in family Cyatheaceae [syn:
         Dicksonia, genus Dicksonia]