- any fern of the genus Polypodium, as P. vulgare, having creeping rootstocks, deeply pinnatifid evergreen fronds, and round, naked sori.
- any of various ferns of the genus Polypodium, esp P. vulgare, having deeply divided leaves and round naked sori: family Polypodiaceae
- any fern of the family Polypodiaceae, all having opaque leaves that are divided in most species
