Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

Medical Dictionary

allantois

play
noun al·lan·to·is \ə-ˈlant-ə-wəs\

Medical Definition of allantois

plural allantoides \ˌal-ən-ˈtō-ə-ˌdēz, ˌal-ˌan-\play play

  1. :  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




Learn More about allantois


Seen and Heard

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

a smart aleck

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image567572573

Which of these is a synonym of unctuous?

maudlin oily angry prompt
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ