a. [ Pref. a- + placental. ] Belonging to the Aplacentata; without placenta. [ 1913 Webster ]
a. (Zool.) Without a placenta, as marsupials and monotremes; nonplacental. --
‖n. pl. [ NL. See In- not, and Placental. ] (Zool.) A primary division of the Mammalia, including the monotremes and marsupials, in which no placenta is formed. [ 1913 Webster ]
a.
n. (Zool.) One of the Placentalia. [ 1913 Webster ]
‖n. pl. [ NL. ] (Zool.) A division of Mammalia including those that have a placenta, or all the orders above the marsupials. [ 1913 Webster ]