The Collaborative International Dictionary of English v.0.48:
Placenta \Pla*cen"ta\, n.; pl. L. Placent[ae], E. Placentas.
[L., a cake, Gr. ? a flat cake, from ? flat, fr. ?, ?,
anything flat and broad.]
1. (Anat.) The vascular appendage which connects the fetus
with the parent, and is cast off in parturition with the
Note: In most mammals the placenta is principally developed
from the allantois and chorion, and tufts of vascular
villi on its surface penetrate the blood vessels of the
parental uterus, and thus establish a nutritive and
excretory connection between the blood of the fetus and
that of the parent, though the blood itself does not
flow from one to the other.
2. (Bot.) The part of a pistil or fruit to which the ovules
or seeds are attached.