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 researchers also found DNA changes related to immune system pathways in the placentas that were exposed to acetaminophen, which was linked to a higher chance of children developing ADHD. —Shiv Sudhakar, FOXNews.com, 27 Mar. 2025

It's also found in the placenta tissue of pregnant people. —Lindsey Desoto, Health, 19 Mar. 2025

The bacteria can infect the placenta if a pregnant person has an untreated Lyme disease infection. —Jennifer Welsh Published, Verywell Health, 3 Feb. 2025

Back in September, the mom of two opened up about her decision to encapsulate her placenta after giving birth to baby Sosa. —Hannah Sacks, People.com, 2 Jan. 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