monotreme

Từ điển WordNet v3.1 - WordNet Dictionary

noun

the most primitive mammals comprising the only extant members of the subclass Prototheria
• Syn:
egg-laying mammal
• Hypernyms:
prototherian
• Hyponyms:
echidna, spiny anteater, anteater, platypus, duckbill,
duckbilled platypus, duck-billed platypus, Ornithorhynchus anatinus