any mammal of the primitive order Monotremata, of Australia and New Guinea: egg-laying toothless animals with a single opening (cloaca) for the passage of eggs or sperm, faeces, and urine. The group contains only the echidnas and the platypus
Derived forms
monotrematous (ˌmɒnəʊˈtriːmətəs)
adjective
Word origin
C19: via New Latin from mono- + Greek trēma hole
monotreme in American English
(ˈmɑnoʊˌtrim; ˈmɑnəˌtrim)
noun
any of the lowest order (Monotremata) of mammals, consisting of the platypus andthe echidnas, which lay eggs and have a single opening for the digestive and urinary tracts and genital organs