Definition of monotreme
: any of an order (Monotremata) of egg-laying mammals comprising the platypuses and echidnas
Recent Examples of monotreme from the Web
There are three kinds of mammals: egg-laying monotremes such as the platypus, marsupials like kangaroos and opossums, and the majority—placental, or eutherian, mammals—including humans and about 4400 other mammal species.
Though monotremes' fossil record is limited, some skulls have been found, such as the extinct Obdurodon dicksoni.
These example sentences are selected automatically from various online news sources to reflect current usage of the word 'monotreme'. Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.
Medical Definition of monotreme
: any mammal (as a platypus) of the order Monotremata
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