noun pl. placentas -·tas or placentae -·tae (-tē)

1. Anat., Zool.
   1. a vascular organ, developed within the uterus of most mammals during gestation from the chorion of the embryo and a part of the maternal uterine wall, that is connected to the embryo by the umbilical cord and that is discharged shortly after birth: it serves as the structure through which nourishment for the fetus is received from, and wastes of the fetus are eliminated into, the circulatory system of the mother
   2. any similar structure in other animals
2. Bot.
   1. that part of the lining of the ovary which bears the ovules
   2. any mass of tissue that bears sporangia or spores

Etymology: ModL < L, lit., a cake < Gr plakounta, acc. of plakous, a flat cake < plax (gen. plakos), a flat object < IE base *plāk-, flat > L placere, to please