marsupial UK /mɑːˈsuː.pi.əl/US /mɑɹˈsu.pi.əl/adjective 2noun 1forms 3 adjective2 •Of or pertaining to a marsupial.Showing that this animal is marsupial, consists of the following characters. — 1892 •Of or relating to a marsupium.the marsupial bones noun1 •A mammal of the infraclass Marsupialia, including those where the female has a pouch in which it rears the young through early infancy, such as kangaroos, koalas, wombats and opossums, as well as the pouchless shrew opossums. formsmarsupials · more marsupial · most marsupial