aplacental

from WordNet (r) 3.0 (2006)
aplacental
    adj 1: having no placenta; "monotremes and marsupials are
           aplacental mammals" [ant: {placental}]
    
from The Collaborative International Dictionary of English v.0.48
Aplacental \Ap`la*cen"tal\, a. [Pref. a- + placental.]
   Belonging to the Aplacentata; without placenta.
   [1913 Webster]
    

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