Placenta

From Medieval Latin placenta uterina ("uterine cake"), from Latin placenta ("flat cake"), because of the flat round shape of the afterbirth.

Full definition of placenta

(plural placentae or placentas)

(anatomy) A vascular organ in mammals, except monotremes and marsupials, present only in the female during gestation. It supplies food and oxygen from the mother to the foetus, and passes back waste. It is implanted in the wall of the uterus and links to the foetus through the umbilical cord. It is expelled after birth.
(botany) In flowering plants, the part of the ovary where ovules develop; in non-flowering plants where the spores develop.