noun Download 🔗Share A mammal that lays eggs and has a single urogenital and digestive orifice. Only the echidnas and platypuses are included in this group Examples : "In their biology class, the students learned that monotremes, such as echidnas and platypuses, are unique mammals because they lay eggs instead of giving birth to live young. " animal biology organism nature Chat with AIVocabulary GamePractice Reading