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

The identical twin boys Ompha and Omphile shared a placenta, while the girls Refiloe and Reneilwe each had their own placentas. —Hannah Sacks, PEOPLE, 8 May 2026

While children do receive some protection from their mothers, antibodies transferred through the placenta wane after birth. —Paul Sisson, San Diego Union-Tribune, 7 May 2026

Del Valle was bleeding due to placenta previa, a rare and life-threatening pregnancy complication in which the placenta blocks or covers the cervix. —Todd Feurer, CBS News, 7 May 2026

At 25 weeks, her placenta had moved to cover her cervix, which put her at a high risk of hemorrhage and a dangerous delivery. —Alyssa Goldberg, USA Today, 4 May 2026

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