plumularia UK /ˌpluː.mjʊˈlɛəɹi.ə/US /ˌplu.mjəˈlɛɹi.ə/ noun1 •(no longer used) A plumed hydroid; any hydrozoan belonging to Plumularia and other genera of the family Plumulariidae, generally growing in plume-like forms. formsplumulariae · plumularias