• (n.) One of the Placentalia. • (a.) Of or pertaining to the Placentalia. • (a.) Of or pertaining to the placenta; having, or characterized by having, a placenta; as, a placental mammal. Found on http://thinkexist.com/dictionary/meaning/placental/
Pla·cen'tal adjective 1. Of or pertaining to the placenta; having, or characterized by having, a placenta; as, a placental mammal. 2. (Zoology) Of or pertaining to the Placentalia. Found on http://www.encyclo.co.uk/webster/P/97
adjective pertaining to or having or occurring by means of a placenta; `all mammals except monotremes and marsupials are placental mammals` Found on https://www.encyclo.co.uk/local/20974