Monotremata :: Monotremata (n. pl.) A subclass of Mammalia, having a cloaca in which the ducts of the urinary, genital, and alimentary systems terminate, as in birds. The female lays eggs like a bird. See Duck mole, under Duck, and Echidna..
Monotrematous :: Monotrematous (a.) Of or pertaining to the Monotremata.