placenta

noun

pla·​cen·​ta plə-ˈsen-tə How to pronounce placenta (audio)
plural placentas or placentae plə-ˈsen-(ˌ)tē How to pronounce placenta (audio)
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

Examples of placenta in a Sentence

Recent Examples on the Web Most people with this infection have little or no symptoms, but there is a unique risk to pregnant women because toxoplasmosis can be transmitted through the placenta. Katia Hetter, CNN, 29 Feb. 2024 Iron needs increase during pregnancy because a pregnant person’s blood volume expands significantly in order to maintain proper circulation and to deliver sufficient oxygen to their own tissues, as well as to the placenta and baby. Casey Seiden, Parents, 26 Feb. 2024 Earlier research in both animals and humans found that cannabis exposure can negatively affect the placenta, which is the source of nutrients and oxygen for the developing fetus. Linda Carroll, NBC News, 12 Dec. 2023 For pregnant women who are in the early stages of a syphilis infection that is left untreated, there’s about a 70% chance that the infectious agent will pass through the placenta to the fetus, Stafford said. Deidre McPhillips, CNN, 13 Feb. 2024 The corpus luteum continues to produce progesterone until about 10 weeks, when the placenta takes over its production. Lambeth Hochwald, Parents, 7 Jan. 2024 But the placenta breaks these rules, according to the new research. Annie Melchor, WIRED, 7 Jan. 2024 In traditional births, Guarani bury the placenta just outside their home’s entrance. Terrence McCoy, Washington Post, 2 Jan. 2024 Additionally, if a pregnant woman is exposed to lead over a long period or has prior high blood levels, the toxin can cross the placenta to the fetus and increase the risk of miscarriage, neurocognitive damage, premature birth or low-birth weight, according to the CDC. Mary Kekatos, ABC News, 6 Dec. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'placenta.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

New Latin, from Latin, flat cake, from Greek plakoenta, accusative of plakoeis, from plak-, plax flat surface — more at fluke entry 2

First Known Use

1638, in the meaning defined at sense 1

Time Traveler
The first known use of placenta was in 1638

Dictionary Entries Near placenta

Cite this Entry

“Placenta.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/placenta. Accessed 18 Mar. 2024.

Kids Definition

placenta

noun
pla·​cen·​ta plə-ˈsent-ə How to pronounce placenta (audio)
plural placentas or placentae -ˈsent-ē How to pronounce placenta (audio)
: the organ in most mammals by which the fetus is joined to the uterus of the mother and is nourished
placental
-ˈsent-ᵊl
adjective

Medical Definition

placenta

noun
pla·​cen·​ta plə-ˈsent-ə How to pronounce placenta (audio)
plural placentas or placentae -ˈsent-(ˌ)ē How to pronounce placenta (audio)
: 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

More from Merriam-Webster on placenta

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