am·ni·on (ămnē-ən, -ŏn′)
n. pl. am·ni·ons or am·ni·a (-nē-ə)
A tough, thin membrane that forms a sac enclosing the embryo or fetus of a mammal, bird, or reptile. It is filled with a serous fluid in which the embryo or fetus is suspended.
[New Latin, from Greek amneion, variant of amneios, amnion, and from amnion, amnion, both from amnos, lamb; akin to Irish úan, Latin agnus, and Old Church Slavonic agnę, lamb.]
am′ni·otic (-ŏtĭk), am′ni·onic (-ŏnĭk) adj.
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