Definition of alismaceous in US English:

alismaceous

adjective

Botany
rare
  • Characteristic of or belonging to the former family Alismaceae (now Alismataceae), comprising monocotyledonous aquatic and marshland plants found chiefly in north temperate regions, of which Alisma is the type genus.

Origin

Mid 19th century. From alisma + -aceous, after scientific Latin Alismaceae, former family name.

Pronunciation

alismaceous

/ˌalɪzˈmeɪʃəs/