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

Isla died after the healthy, viable fetus in the 22nd week of gestation had no oxygen when the placenta tore and bled as a result of the crash, according to the suit. —Corina Vanek, AZCentral.com, 4 July 2025

The placenta is connected to a developing fetus by a tubelike structure called the umbilical cord. —Beth Warren, The Tennessean, 2 July 2025

After being asked by an audience member about whether to scan a woman with low HCG levels, the hormone produced by the placenta during pregnancy, a doctor urged that audience member to turn the woman away and be seen by her medical provider. —Abigail Brooks, NBC news, 23 June 2025

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

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