pla·cen·tal /-əl/ 形容詞
  胎盤的
  Pla·cen·tal a.
  1. Of or pertaining to the placenta; having, or characterized by having, a placenta; as, a placental mammal.
  2. Zool. Of or pertaining to the Placentalia.
  Pla·cen·tal, n. Zool. One of the Placentalia.
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  placental
       adj : of or having or occurring by means of a placenta; "all
             mammals except monotremes and marsupials are placental
             mammals" [ant: aplacental]
       n : mammals having a placenta; all mammals except monotremes and
           marsupials [syn: placental mammal, eutherian, eutherian
           mammal]