Definition of monopleurid in US English:

monopleurid

noun

rare
  • A fossil bivalve mollusc of the family Monopleuridae (now usually included in the family Caprotinidae).

Origin

Early 20th century; earliest use found in Archibald Geikie (1835–1924), geologist and historian. From scientific Latin Monopleura, genus name + -id, after scientific Latin Monopleuridae, family name.