Definition of medullosan in US English:

medullosan

adjective

Botany
  • Of, relating to, or belonging to the group of extinct seed-bearing ferns (pteridosperms) including the genus Medullosa, known from Carboniferous and Permian fossils, whose stems have large, widely-spaced petioles and branched vascular cylinders.

noun

Botany
  • A seed-bearing fern of the extinct genus Medullosa or the group to which it belongs.

Origin

Early 20th century; earliest use found in Philosophical Transactions of the Royal Society of London. From Medullosa + -an.

Pronunciation

medullosan

/ˌmɛdəˈləʊsn/