Metatherian

Part of speech: noun, adjective

Definitions

1. Any mammal belonging to the group that includes marsupials such as kangaroos and opossums along with their extinct relatives
2. A pouched or pouchless mammal classified within the taxonomic group of marsupials and related extinct forms
3. An animal from the infraclass of mammals whose young are typically born at an early stage and nurtured in a pouch

Etymology: "Metatherian" is a technical coinage from modern zoology rather than an old word with a long pedigree. It is formed from "Metatheria," the name of the group that includes marsupials, which was itself built from Greek roots: "meta," meaning "after" or "beyond," and "therion," meaning "wild beast." The name reflects the placement of the group among mammals, but the choice of "beyond" rather than something more descriptive points to the scientists' classification scheme rather than to any ancient usage. The suffix "-an" is a common English adjective-forming ending, here meaning "belonging to" or "relating to," so a metatherian is any member of that group, and the word also works as an adjective describing its members. Like the group name it is built on, the word is a product of the scientific classification of animals, and it carries no meaning beyond its zoological sense.