placenta

American  

[pluh-sen-tuh] / pləˈsɛn tə /

noun

placentas, plural placentae plural

1. Anatomy, Zoology. the organ in most mammals, formed in the lining of the uterus by the union of the uterine mucous membrane with the membranes of the fetus, that provides for the nourishment of the fetus and the elimination of its waste products.

2. Botany.

   1. the part of the ovary of flowering plants that bears the ovules.

   2. (in ferns and related plants) the tissue giving rise to sporangia.

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placenta British  

/ pləˈsɛntə /

noun

1. the vascular organ formed in the uterus during pregnancy, consisting of both maternal and embryonic tissues and providing oxygen and nutrients for the fetus and transfer of waste products from the fetal to the maternal blood circulation See also afterbirth

2. the corresponding organ or part in certain mammals

3. botany

   1. the part of the ovary of flowering plants to which the ovules are attached

   2. the mass of tissue in nonflowering plants that bears the sporangia or spores

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placenta Scientific  

/ plə-sĕn′tə /

1. The sac-shaped organ that attaches the embryo or fetus to the uterus during pregnancy in most mammals. Blood flows between mother and fetus through the placenta, supplying oxygen and nutrients to the fetus and carrying away fetal waste products. The placenta is expelled after birth.

2. The part of the ovary of a flowering plant to which the ovules are attached. In a green pepper, for example, the whitish tissue to which the seeds are attached is the placenta.

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placenta Cultural  

1. An organ that forms in the uterus after the implantation of a zygote. The placenta moves nourishment from the mother's blood to the embryo or fetus; it also sends the embryo or fetus's waste products into the mother's blood to be disposed of by the mother's excretory system. The embryo or fetus is attached to the placenta by the umbilical cord. After birth, the placenta separates from the uterus and is pushed out of the mother's body.

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Other Word Forms

Derived Forms

• subplacenta
  noun
• interplacental
  adjective
• nonplacental
  adjective
• placental
  adjective
• placentary
  adjective
• preplacental
  adjective
• subplacental
  adjective

Inflected Forms

Nouns

• placentae
  plural
• placentas
  plural

Etymology

Origin of placenta

First recorded in 1670–80; from New Latin: “something having a flat, circular form,” Latin: “cake,” from Greek plakóenta, accusative of plakóeis “flat cake,” derivative of pláx (stem plak- ) “flat”

Explanation

The organ that provides nourishment to developing fetuses before they're born is called a placenta. Most mammals get their nutrients from their mother through the placenta until birth; then they have to look elsewhere... The placenta is commonly called the afterbirth, since it's expelled from the mother's body after a baby is born. A placenta has the unique position of acting as a temporary organ, growing along with the fetus (or fetuses) it feeds, but completely unnecessary after birth. Human placentas are round and flat, and maybe that's why they got their name from the Latin for "cake," placenta.

Example Sentences

See Examples For:

placenta placentae placentas

All newborns lack vitamin K. No matter how much vitamin K a mother consumes, it doesn’t sufficiently pass through the placenta, and breast milk contains only small amounts.

From Salon ● May 7, 2026

"They've given me the medicines and insulin I need for the health of baby and the placenta."

From BBC ● Mar. 24, 2026

Late in her third trimester, doctors diagnosed her with placenta accreta, a potentially life-threatening condition in which the placenta grows too far into the wall of the uterus.

From The Wall Street Journal ● Dec. 28, 2025

They have already been detected in breast milk and in the placenta -- and even in the brain.

From Science Daily ● Dec. 22, 2025

It turned out to be placenta, and washed off.

From "Middlesex: A Novel" by Jeffrey Eugenides

One point makes the above view more probable in Acropera than in other cases, viz. the presence of rudimentary placentae or testae, for I cannot hear that these have been observed in the male plants.

From More Letters of Charles Darwin — Volume 2 by Darwin, Francis, Sir

In making longitudinal sections of the fertilised ovary before mentioned, I found the basal portion entirely destitute of ovules, their place being substituted by transparent cellular ramification of the placentae.

From More Letters of Charles Darwin — Volume 2 by Darwin, Francis, Sir

As I traced the placentae upwards, the ovules appeared, becoming gradually more abundant towards its apex.

From More Letters of Charles Darwin — Volume 2 by Darwin, Francis, Sir

Yet when I call to mind the state of the placentae in A. luteola, I am astonished that they should produce ovules.

From More Letters of Charles Darwin — Volume 2 by Darwin, Francis, Sir

Two placentae were expelled some time after the twins, and showed a membranous junction.

From Anomalies and Curiosities of Medicine by Pyle, Walter L. (Walter Lytle)

She was carrying an unknown number of human placentas in a plastic bag when she was picked up, according to the police.

From BBC ● Sep. 19, 2025

The examples included an NPR story on eating human placentas, a practice that has been around for decades, and a 2017 documentary about a transgender teen on PBS.

From Los Angeles Times ● May 2, 2025

Some placentas have evolved to be disklike, some are leaf-shaped, some ring-shaped, heart-shaped; some are ridged, branched, labyrinthine, or weblike.

From Slate ● Sep. 7, 2024

While the advanced pathology residents were working on cancer, Kliman said newer residents started in the basement morgue performing autopsies on placentas and fetuses.

From Salon ● May 29, 2024

In 2006, some seven hundred new mothers found out that doctors had taken their placentas without consent to test for abnormalities that might help the hospital defend itself against future lawsuits over birth defects.

From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot

Related Words

• sheath
• sheet