Definition of: placenta

(plə·sen′tə) noun plural ·tas or ·tae (-tē)
1. Anat. In higher mammals, the vascular, spongy organ of interlocking fetal and maternal tissue by which the fetus is nourished in the uterus.
2. Bot. The part of the ovary that supports the ovules. [<NL placenta (uterina) (uterine) cake <L, a cake <Gk. plakoeis, -oentos a flat cake <plax, plakos a flat plate]
—pla·cen′tal, plac·en·tar·y (plas′ən·ter′ē, plə·sen′tər·ē) adjective