eu·ther·i·an 
(y-thîrē-ən)
(y-thîrē-ən)n.
Any of various mammals of the infraclass Eutheria, including all of the species, such as primates, carnivores, whales, ruminants, bats, and rodents, in which the female bears live young that are nourished before birth by means of a complex placenta. Also called placental mammal.
[From New Latin Euthēria, infraclass name : Greek eu-, eu- + Greek thēria, pl. of thērion, wild animal; see TREACLE.]
eu·theri·an adj.