amnion

noun
am·​ni·​on | \ ˈam-nē-ˌän How to pronounce amnion (audio) , -ən \
plural amnions or amnia\ ˈam-​nē-​ə How to pronounce amnion (audio) \

Definition of amnion

1 : a thin membrane forming a closed sac about the embryos or fetuses of reptiles, birds, and mammals and containing the amniotic fluid
2 : a membrane analogous to the amnion and occurring in various invertebrates

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Other Words from amnion

amniotic \ ˌam-​nē-​ˈä-​tik How to pronounce amnion (audio) \ adjective

Examples of amnion in a Sentence

Recent Examples on the Web Birds, mammals and reptiles called amniotes produce eggs that include an amnion, or inner membrane, that keeps the embryo inside from drying out. Ashley Strickland, CNN, "Fossil egg discoveries, including one in Antarctica, show dinosaurs and marine reptiles laid soft-shell eggs," 17 June 2020 Stem cells, platelet rich plasma (PRP), placenta/amnion and their variants are the latest rage. Profootballdoc, sandiegouniontribune.com, "New NFL treatments make news, don't always work," 1 Sep. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'amnion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of amnion

1661, in the meaning defined at sense 1

History and Etymology for amnion

New Latin, from Greek, caul, from amnos lamb — more at yean

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Cite this Entry

“Amnion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/amnion. Accessed 16 May. 2021.

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More Definitions for amnion

amnion

noun
am·​ni·​on | \ ˈam-nē-ˌän, -ən How to pronounce amnion (audio) \
plural amnions or amnia\ -​nē-​ə How to pronounce amnion (audio) \

Medical Definition of amnion

: a thin membrane forming a closed sac about the embryos and fetuses of reptiles, birds, and mammals and containing the amniotic fluid

called also amniotic sac

More from Merriam-Webster on amnion

Britannica.com: Encyclopedia article about amnion

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