Definition of Monotremata in US English:

Monotremata

noun

Zoology
  • Treated as plural. The single order of mammals included in the subclass Prototheria, comprising egg-laying mammals which which have a common opening for the urogenital and digestive systems; animals of this order (collectively or individually), monotremes.

Origin

Mid 19th century; earliest use found in Richard Owen (1804–1892), comparative anatomist and palaeontologist. From scientific Latin Monotremata, order name from ancient Greek μονο- + τρηματ-, τρῆμα hole, orifice.