pla·cen·ta
n. pl. pla·cen·tas or pla·cen·tae
1.
a. A membranous vascular organ that develops in female mammals during pregnancy, lining the uterine wall and partially enveloping the fetus, to which it is attached by the umbilical cord. Following birth, the placenta is expelled.
b. An organ with similar functions in some nonmammalian animals, such as certain sharks and reptiles.
2. Botany
The part within the ovary of a flowering plant to which the ovules are attached.