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-​ \

Definition of allantois

: 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

Other Words from allantois

allantoic \ ˌa-​lən-​ˈtō-​ik How to pronounce allantois (audio) , ˌa-​ˌlan-​ \ adjective

First Known Use of allantois

1615, in the meaning defined above

History and Etymology for allantois

New Latin, ultimately from Greek allant-, allas sausage

Keep scrolling for more

Learn More about allantois

Time Traveler for allantois

Time Traveler

The first known use of allantois was in 1615

See more words from the same year

Statistics for allantois

Cite this Entry

“Allantois.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/allantois. Accessed 3 Mar. 2021.

Style: MLA
MLA Chicago APA Merriam-Webster

Keep scrolling for more

More Definitions for allantois

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) \

Medical Definition of allantois

: 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

Comments on allantois

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

WORD OF THE DAY

Test Your Vocabulary

February 2021 Words of the Day Quiz

  • squirrel in winter
  • Which is a synonym of perdure?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
 AlphaBear 2

Spell words. Make bears.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!