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)
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
amniotic adjective

Examples of amnion in a Sentence

Recent Examples on the Web Several important features of real embryos are present in the mimics, the team says, including the predecessors of sperm and eggs and the beginnings of the amnion, the membrane-like structure that encloses the embryo in a watery environment. Bymitch Leslie, science.org, 17 June 2023 Additional features can be built into these sensors such as amnion fluid infusion and extraction. IEEE Spectrum, 13 Dec. 2018 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, 17 June 2020 Stem cells, platelet rich plasma (PRP), placenta/amnion and their variants are the latest rage. Profootballdoc, sandiegouniontribune.com, 1 Sep. 2017

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'amnion.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

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

First Known Use

1661, in the meaning defined at sense 1

Time Traveler
The first known use of amnion was in 1661

Dictionary Entries Near amnion

Cite this Entry

“Amnion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/amnion. Accessed 18 Mar. 2024.

Kids Definition

amnion

noun
am·​ni·​on ˈam-nē-ˌän How to pronounce amnion (audio)
: a thin membrane forming a closed sac about the embryo or fetus of a reptile, bird, or mammal and containing a watery fluid in which the embryo or fetus is immersed

Medical Definition

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)
: 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

Love words? Need even more definitions?

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