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

borrowed from New Latin, probably taken as singular of earlier allantoidēs in the same sense, borrowed from Greek allantoeidḗs "sausage-like" (in allantoeidḕs hymḗn "allantois," literally, "sausage-like membrane"), from allant-, allâs "sausage" (of uncertain origin) + -oeidḗs -oid entry 2

First Known Use

1615, in the meaning defined above

Time Traveler
The first known use of allantois was in 1615

Dictionary Entries Near allantois

allantoinase

allantois

allantoxaidin

See More Nearby Entries 

Cite this Entry

“Allantois.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/allantois. Accessed 25 Nov. 2024.

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Medical Definition

allantois

noun
al·​lan·​to·​is ə-ˈlant-ə-wəs How to pronounce allantois (audio)
plural allantoides ˌal-ən-ˈtō-ə-ˌdēz How to pronounce allantois (audio) ˌal-ˌan- 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

More from Merriam-Webster on allantois

Britannica.com: Encyclopedia article about allantois

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