polypodiaceous,a.Bot.|ˌpɒlɪpəʊdɪˈeɪʃəs| [f.mod.L. Polypodiāce-æ, f. Polypodium: see -aceous.] Belonging to the family (or sub-family) Polypodiaceæ, comprising the large majority of ferns. 1852Th. Ross Humboldt's Trav. I. viii. 282 A beautiful fern,..a new genus of the order of polypodiaceous plants.1858in Mayne Expos.Lex.