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

Examples of placenta in a Sentence

Recent Examples on the Web

In contrast, evidence from people vaccinated during pregnancy show that newborns receive protective immunity through antibodies that cross the placenta and are found in breast milk, Chin-Hong explains. —Lauren J. Young, Scientific American, 10 June 2025

Microplastics have also been found in lung tissue and human placentas, raising concerns about toxicity and chronic inflammation. —Dianne Plummer, Forbes.com, 31 May 2025

Placental abruption The premature separation of the placenta from the uterine wall is known as a placental abruption. —Lisa McCarty, SELF, 21 May 2025

They’ve been detected in human tissue, including the placenta, as well as in breast milk, urine and blood. —Denise Maher, Flow Space, 23 Apr. 2025

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

Rhymes for placenta

• magenta
• momenta
• placentae
• impedimenta
• presidente

Kids Definition

placenta

noun

pla·​cen·​ta plə-ˈsent-ə 

plural placentas or placentae -ˈsent-ē 

: 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 

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