pla·​cen·​tal | \ plə-ˈsen-tᵊl How to pronounce placental (audio) \

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 The report said the spike protein in coronavirus is the same as another spike protein called syncytin-1, which is involved in placental growth during pregnancy. Carmina Tiscareño, Dallas News, "Doctors debunk myths and false information about the COVID-19 vaccine," 4 Feb. 2021 By analyzing these cases, the team identified two unusual placental abnormalities that seemed to occur in all the patients. Mariana Lenharo, Scientific American, "Why COVID Vaccines Are Likely Safe for Pregnant People," 2 Feb. 2021 The high-probability patients are offered a more invasive diagnostic test using DNA either from the fetal cells floating in the amniotic fluid (amniocentesis) or from placental tissue (chorionic villus sampling). Sarah Zhang, The Atlantic, "The Last Children of Down Syndrome," 18 Nov. 2020 The last common ancestor of monotremes like platypuses, marsupials like opossums, and placental mammals like flying squirrels lived about 150 million years ago, reports Gizmodo. Theresa Machemer, Smithsonian Magazine, "Platypuses Glow Green Under Ultraviolet Light," 3 Nov. 2020 Now, researchers have devised a way to derive and observe early precursors of placental cells in a dish. Kelly Servick, Science | AAAS, "Stem cells offer new glimpse at how the placenta emerges—and how the fetus-sustaining organ can fail," 30 Sep. 2020 Unfortunately, in some cases, placental abruption can cause premature birth or stillbirth. Sarah Jacoby, SELF, "Chrissy Teigen Just Wrote an Emotional, Revealing Essay About Losing Her Baby," 27 Oct. 2020 In a Medium post on Tuesday, Teigen explained that her doctors had diagnosed her with a partial placental abruption. NBC News, "'It was time to say goodbye': Chrissy Teigen writes about pregnancy loss and public grief," 1 Oct. 2020 If the interface is weak, bleeding may occur, which can ultimately lead to premature separation of the placenta from the uterus—known as placental abruption. Claire Gillespie,, "Chrissy Teigen Reveals Miscarriage of Her Baby Boy: 'The Kind of Pain We’ve Never Felt Before’," 1 Oct. 2020 Recent Examples on the Web: Noun Origolestes is an ancestor to therian mammals, the group that includes all placentals and marsupials alive today. Jim Daley, Scientific American, "Now Hear This: New Fossils Reveal Early Ear-Bone Evolution," 5 Dec. 2019 For example, the specific type of placental cell where Zika can lurk in humans isn't thought to be present in mouse placentas., "Patients will pay for the crackdown on fetal tissue research, scientists fear," 10 June 2019 For example, the specific type of placental cell where Zika can lurk in humans isn’t thought to be present in mouse placentas. Washington Post, "Scientists feel chill of crackdown on fetal tissue research," 9 June 2019 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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Time Traveler for placental

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The first known use of placental was in 1785

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Statistics for placental

Last Updated

13 Feb 2021

Cite this Entry

“Placental.” Dictionary, Merriam-Webster, Accessed 5 Mar. 2021.

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More Definitions for placental


pla·​cen·​tal | \ -əl How to pronounce placental (audio) \

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)

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