allantois

noun

al·​lan·​to·​is ə-ˈlan-tə-wəs How to pronounce allantois (audio)
plural allantoides ˌa-lən-ˈtō-ə-ˌdēz How to pronounce allantois (audio)
ˌa-ˌlan-
: a vascular fetal membrane of reptiles, birds, and mammals that is formed as a pouch from the hindgut and that in placental mammals is intimately associated with the chorion in formation of the placenta
allantoic
ˌa-lən-ˈtō-ik How to pronounce allantois (audio)
ˌa-ˌlan-
adjective

Word History

Etymology

New Latin, ultimately from Greek allant-, allas sausage

First Known Use

1615, in the meaning defined above

Time Traveler
The first known use of allantois was in 1615

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Cite this Entry

“Allantois.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/allantois. Accessed 19 Mar. 2024.

Medical Definition

allantois

noun
al·​lan·​to·​is ə-ˈlant-ə-wəs How to pronounce allantois (audio)
: a vascular fetal membrane of reptiles, birds, or mammals that is formed as a pouch from the hindgut and that in placental mammals is intimately associated with the chorion in formation of the placenta

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