Definition of osmundaceous in US English:

osmundaceous

adjective

Botany
  • Belonging to or characteristic of the family Osmundaceae of ferns, of which Osmunda is the type genus.

Origin

Mid 19th century; earliest use found in William T. Brande (1788–1866), chemist. From scientific Latin Osmundaceae; from Osmunda + -aceous: see -aceous) + -ous.