pla·cen·tal | \plə-ˈsen-tᵊl \

Definition of placental 

(Entry 1 of 2)

1 : of, relating to, having, or occurring by means of a placenta

2 : eutherian



Definition of placental (Entry 2 of 2)

: a placental mammal : eutherian

Examples of placental in a Sentence

Recent Examples on the Web: Adjective

Almost all organisms on Earth do, from animals and plants to bacteria and fungi, but at some point in their history, placental mammals like us stopped producing enzymes that heal DNA with light. Robbie Gonzalez, WIRED, "DNA-Repairing Sunscreen: Legit or Not?," 2 July 2018 This also meant that testicondy evolved after afrotherians split from other placental mammals, about 100 million years ago, which suggests the common ancestor of all mammals did indeed lower their testes, Dr. Hiller said. New York Times, "The Evolutionary Origin of Descending Testicles," 29 June 2018 This abuse was part of a larger prejudice against marsupials that is sometimes called placental chauvinism. Brooke Jarvis, The New Yorker, "The Obsessive Search for the Tasmanian Tiger," 16 Jan. 2012 Quake compared the activity of genes found in the mother’s blood, which included the proteins, enzymes and other products made by the mother’s genes, placental genes and fetal genes. Alice Park, Time, "There May Soon Be a Blood Test for Predicting Premature Births," 7 June 2018 As a second part of the study, the researchers also analyzed gene expression in placental tissue from patients whose mothers had or didn't have pregnancy complications. Mark Lieber, CNN, "Pregnancy complications might 'turn on' schizophrenia genes, study says," 30 May 2018 The most common causes include genetic or placental abnormalities, complications with labor (such as preterm labor), and issues with the umbilical cord. Korin Miller, SELF, "NHL Star Erik Karlsson and His Wife Lost Their Son a Month Before He Was Due," 22 Mar. 2018 As placental mammals, rabbits develop embryos inside a uterus and, after a pregnancy lasting about 31 to 33 days, give birth to a litter of often 12 or more bunnies. Taysha Murtaugh, Woman's Day, "'Do Bunnies Lay Eggs?' Is an Actual Question People Ask Google," 15 Feb. 2018 Due to a placental abruption, which caused severe blood loss to both Countess Sophie and Lady Louise, she was delivered by the Royal Surgeon and Gynecologist Marcus Setchell via emergency Caesarean section. Chanel Vargas, Town & Country, "Who Is the Queen's Youngest Granddaughter, Lady Louise Windsor," 29 Dec. 2017

Recent Examples on the Web: Noun

Each increase of 5 micrograms per cubic meter in exposure was associated with 9% shorter cord blood telomeres and 13% shorter placental telomeres, the researchers estimated. Susan Scutti, CNN, "Exposure to air pollution before birth may shorten our lives," 16 Oct. 2017 The researchers reported that the Zika virus binds consistently to a protein in different placental cells called TIM1. Pam Belluck, New York Times, "Confronting a Lingering Question About Zika: How It Enters the Womb," 18 July 2016 There are three kinds of mammals: egg-laying monotremes such as the platypus, marsupials like kangaroos and opossums, and the majority—placental, or eutherian, mammals—including humans and about 4400 other mammal species. Elizabeth Pennisi, Science | AAAS, "Digital reconstruction of ancient chromosomes reveals surprises about mammalian evolution," 19 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'placental.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of placental


1785, in the meaning defined at sense 1


1839, in the meaning defined above

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The first known use of placental was in 1785

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More Definitions for placental


pla·cen·tal | \-əl \

Medical Definition of placental 

(Entry 1 of 2)

1 : of, relating to, having, involving, or produced by a placenta placental lactogen placental defects

2 : of or relating to placental mammals



Medical Definition of placental (Entry 2 of 2)

More from Merriam-Webster on placental

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Comments on placental

What made you want to look up placental? Please tell us where you read or heard it (including the quote, if possible).


exaggeratedly or childishly emotional

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