placental mammal pla·cen·tal·mammal uncommon noun 1. mammals having a placenta; all mammals except monotremes and marsupials Synonymsplacentalplacental mammaleutherianeutherian mammal Related words Broader terms mammal Narrower terms livestockbullcowyearlingbuckdoeinsectivoreaquatic mammal Parts Eutheria WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
