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amnion

[am-nee-uh n] /ˈæm ni ən/
noun, plural amnions, amnia
[am-nee-uh] /ˈæm ni ə/ (Show IPA)
1.
Anatomy, Zoology. the innermost of the embryonic or fetal membranes of reptiles, birds, and mammals; the sac in which the embryo is suspended.
2.
Zoology. a similar membrane of insects and other invertebrates.
Origin
1660-1670
1660-70; < Greek, equivalent to amn(ós) lamb (see yean) + -ion diminutive suffix
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for amnion
  • Amniotic constriction bands are caused by damage to a part of the placenta called the amnion.
British Dictionary definitions for amnion

amnion

/ˈæmnɪən/
noun (pl) -nions, -nia (-nɪə)
1.
the innermost of two membranes enclosing an embryonic reptile, bird, or mammal See also chorion
Word Origin
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
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Word Origin and History for amnion
n.

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."

Online Etymology Dictionary, © 2010 Douglas Harper
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amnion in Medicine

amnion am·ni·on (ām'nē-ən, -ŏn')
n. am·ni·ons or am·ni·a (-nē-ə)
The thin, membranous sac filled with a serous fluid in which the embryo or fetus is enclosed and suspended in the uterus. Also called amniotic sac.


am'ni·ot'ic (-ŏt'ĭk) or am'ni·on'ic (-ŏn'ĭk) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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amnion in Science
amnion
  (ām'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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for amnion

in reptiles, birds, and mammals, a membrane forming a fluid-filled cavity (the amniotic sac) that encloses the embryo. The amniotic sac and the fluid it contains are sometimes referred to as the bag of waters

Learn more about amnion with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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