Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A membranous vascular organ that develops in female eutherian mammals during pregnancy, lining the uterine wall and partially enveloping the fetus, to which it is attached by the umbilical cord. Following birth, the placenta is expelled.
  • noun A similar organ in marsupial mammals, consisting of a yolk sac attached to the uterine wall.
  • noun An organ with similar functions in some nonmammalian animals, such as certain sharks and reptiles.
  • noun Botany The part within the ovary of a flowering plant to which the ovules are attached.

from The Century Dictionary.

  • noun In zoöl., anat., and medicine: The organ of attachment of a vertebrate embryo or fetus to the wall of the uterus or womb of the female.
  • noun In echinoderms, a flat discoidal sea-urchin, as a sand-dollar or cake-urchin: used in a generic sense by Klein, 1734.
  • noun [capitalized] A genus of bivalve mollusks, now called Plaruna.
  • noun In botany, that part of the ovary of flowering plants which bears the ovules.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Anat.) The vascular appendage which connects the fetus with the parent, and is cast off in parturition with the afterbirth.
  • noun (Bot.) The part of a pistil or fruit to which the ovules or seeds are attached.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun anatomy A vascular organ in mammals, except monotremes and marsupials, present only in the female during gestation. It supplies food and oxygen from the mother to the foetus, and passes back waste. It is implanted in the wall of the uterus and links to the foetus through the umbilical cord. It is expelled after birth.
  • noun botany In flowering plants, the part of the ovary where ovules develop; in non-flowering plants where the spores develop.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun the vascular structure in the uterus of most mammals providing oxygen and nutrients for and transferring wastes from the developing fetus
  • noun that part of the ovary of a flowering plant where the ovules form

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[New Latin, from Latin, flat cake, alteration of Greek plakoenta, from accusative of plakoeis, flat, from plax, plak-, flat land, surface; see plāk- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Medieval Latin placenta uterina ("uterine cake"), from Latin placenta ("flat cake"), because of the flat round shape of the afterbirth.

Examples

  • They say the placenta is a rich source of stem cells capable of transforming into many types of cells in the body, holding out the hope of using them to treat many human ailments including spinal-cord injury and diabetes.

    Stem Cell Research May Still Continue After Veto | Impact Lab

  • And unless the little sack [folliculus] of the placenta is the intermediary between the falling blood and the child, [the blood] by penetrating would kill him who is exposed.

    A Tender Age: Cultural Anxieties over the Child in the Twelfth and Thirteenth Centuries

  • I had what they called placenta previa and I nearly bled to death and had a terrible time, but while I was in the hospital, soon thereafter, I was very ill and had to have blood transfusions.

    Oral History Interview with Virginia Foster Durr, March 13, 14, 15, 1975. Interview G-0023-1. Southern Oral History Program Collection (#4007)

  • Turns out I didn't write a newsletter for your 59th month, and I blame that entirely on what I call placenta brain, the situation that occurs when a pregnant woman's blood supply is so concentrated on growing someone else's fingers and toes that her brain doesn't have enough juice to complete simple tasks.

    dooce® main feed

  • And, last of all, the first scan showed that, this time, the placenta is placed towards my back, effectively removing a potential frontal shock absorber from the equation.

    sex

  • And, last of all, the first scan showed that, this time, the placenta is placed towards my back, effectively removing a potential frontal shock absorber from the equation.

    knocked update

  • In addition, although cows "share" their blood with their unborn calves, the bovine placenta is a natural filter.

    Mad-cow Disease

  • Exchange of respiratory gases (oxygen and carbon dioxide) across the placenta from the mother to the fetus and from the fetus to the mother.

    Glossary

  • Flow of blood across the placenta from the mother to the fetus and from the fetus to the mother.

    Glossary

  • When the placenta grows across the opening of the cervix, it is described as a placenta previa.

    Our Bodies, Ourselves: Pregnancy and Birth

Comments

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  • See comments on julia's list.

    January 17, 2008