Placentalia is a group of mammals. The majority of living mammals are placental: the other two living mammal groups are the Monotremata and the Marsupialia. The placentals are distinguished from other mammals in that the fetus is nourished during gestation via a placenta while, in general, this is not the case with other mammals (Bandicoots are an...
• (n. pl.) A division of Mammalia including those that have a placenta, or all the orders above the marsupials.
Plac`en·ta'li·a noun plural [ New Latin ] (Zoology) A division of Mammalia including those that have a placenta, or all the orders above the marsupials. 
Type: Term Pronunciation: pla′sen-tā′lē-ă See: Eutheria