amnion

[ am-nee-uh n ]

/ ˈæm ni ən /

SEE MORE SYNONYMS FOR amnion ON THESAURUS.COM

noun, plural am·ni·ons, am·ni·a [am-nee-uh] /ˈæm ni ə/.

Anatomy, Zoology. the innermost of the embryonic or fetal membranes of reptiles, birds, and mammals; the sac in which the embryo is suspended.

Zoology. a similar membrane of insects and other invertebrates.

RELATED WORDS

afterbirth, placenta

Nearby words

amniocentesis, amniochorial, amniogenesis, amniography, amnioma, amnion, amnion nodosum, amnionic, amnionitis, amniorrhea, amniorrhexis

Origin of amnion

1660–70; < Greek, equivalent to amn(ós) lamb (see yean) + -ion diminutive suffix

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for amnion

A very early condition of Man, with yelk-sac, allantois, and amnion (original).
Lectures and Essays|T.H. Huxley
The embryo thus enclosed in the egg finds its protection in the fact that it is encased in a fluid contained in the amnion.
The Meaning of Evolution|Samuel Christian Schmucker
This second fold gives rise to the amnion, and is limited entirely to the somatopleure.
The Works of Francis Maitland Balfour, Volume III (of 4)|Francis Maitland Balfour
The amnion forms a small fold covering over the cephalic extremity of the embryo, which is deeply embedded in the yolk.
The Works of Francis Maitland Balfour, Volume 1|Francis Maitland Balfour

They are the chorion and the amnion; besides which, there are two others that require notice, viz.
A System of Midwifery|Edward Rigby

British Dictionary definitions for amnion

amnion

/ (ˈæmnɪən) /

noun plural -nions or -nia (-nɪə)

the innermost of two membranes enclosing an embryonic reptile, bird, or mammalSee also chorion

Word Origin for amnion

C17: via New Latin from Greek: a little lamb, from amnos a lamb

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for amnion

amnion

1660s, Modern Latin, from Greek amnion "membrane around a fetus," said to be originally "bowl in which the blood of victims was caught" [Liddell & Scott], which is variously said to be of unknown origin, from ame "bucket," or a diminutive of amnos "lamb."

Medicine definitions for amnion

amnion

[ ăm′nē-ən, -ŏn′ ]

n. pl. am•ni•ons

The thin, membranous sac filled with a serous fluid in which the embryo or fetus is enclosed and suspended in the uterus.amniotic sac

Related formsam′ni•ot′ic (-ŏt′ĭk) null adj.

Science definitions for amnion

amnion

[ ăm′nē-ən ]

A thin, membranous sac filled with a watery fluid (called the amniotic fluid) in which the embryo or fetus of a reptile, bird, or mammal is suspended during prenatal development. Also called amniotic sac