placenta
noun
pla·cen·ta plə-ˈsen-tə 
plural placentas or placentae plə-ˈsen-(ˌ)tē
1
: the vascular organ in mammals except monotremes and marsupials that unites the fetus to the maternal uterus and mediates its metabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues
also : an analogous organ in another animal
2
: a sporangium-bearing surface
especially : the part of the carpel bearing ovules
Example Sentences
Recent Examples on the Web Here again, the Rimac is unexpectedly normal-sized—as compared to the placenta-like fit of the Aston Martin Valkyrie, for example. 
Dan Neil, WSJ, 26 Aug. 2022 The university's Institutional Animal Care and Use Committee June report said the pregnant female died overnight after its placenta ruptured while in labor. Rob O'dell, The Arizona Republic, 17 Aug. 2022 She had been previously been put on bed rest and subsequently hospitalized due to excessive bleeding from her placenta. Andrea Wurzburger, Peoplemag, 4 Aug. 2022 The virus may also pass to a fetus through the placenta. Virginia Langmaid, CNN, 5 Aug. 2022 The antibodies from the vaccine have been shown to transfer through the placenta. Duaa Eldeib, ProPublica, 4 Aug. 2022 Pregnant people can also spread the virus to a fetus through the placenta. The Courier-Journal, 25 July 2022 Pregnant people can spread monkeypox to their fetus through the placenta. Emily Deletter, The Enquirer, 21 July 2022 Pregnant women face a higher risk of severe illness from a coronavirus infection, and recent research has shown that the virus can attack and destroy the placenta, leading to stillbirth. NBC News, 15 Feb. 2022 See More
Dan Neil, WSJ, 26 Aug. 2022 The university's Institutional Animal Care and Use Committee June report said the pregnant female died overnight after its placenta ruptured while in labor. Rob O'dell, The Arizona Republic, 17 Aug. 2022 She had been previously been put on bed rest and subsequently hospitalized due to excessive bleeding from her placenta. Andrea Wurzburger, Peoplemag, 4 Aug. 2022 The virus may also pass to a fetus through the placenta. Virginia Langmaid, CNN, 5 Aug. 2022 The antibodies from the vaccine have been shown to transfer through the placenta. Duaa Eldeib, ProPublica, 4 Aug. 2022 Pregnant people can also spread the virus to a fetus through the placenta. The Courier-Journal, 25 July 2022 Pregnant people can spread monkeypox to their fetus through the placenta. Emily Deletter, The Enquirer, 21 July 2022 Pregnant women face a higher risk of severe illness from a coronavirus infection, and recent research has shown that the virus can attack and destroy the placenta, leading to stillbirth. NBC News, 15 Feb. 2022 See More Word History
Etymology
New Latin, from Latin, flat cake, from Greek plakoenta, accusative of plakoeis, from plak-, plax flat surface — more at fluke
First Known Use
1638, in the meaning defined at sense 1
Kids Definition
placenta
noun
pla·cen·ta plə-ˈsen-tə
: the organ in most mammals by which the fetus is joined to the uterus of the mother and is nourished
Medical Definition
placenta
noun
pla·cen·ta plə-ˈsent-ə
plural placentas or placentae -ˈsent-(ˌ)ē
: the vascular organ in mammals except monotremes and marsupials that unites the fetus to the maternal uterus and mediates its metabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues permitting exchange of material by diffusion between the maternal and fetal vascular systems but without direct contact between maternal and fetal blood and typically involving the interlocking of fingerlike vascular chorionic villi with corresponding modified areas of the uterine mucosa see abruptio placentae