am|ni|on

am|ni|on «AM nee uhn», noun, plural -ni|ons, -ni|a «-nee uh».

a membrane forming the inner sac which encloses the embryo or fetus of the higher vertebrates, such as mammals, birds, and reptiles. The amnion is filled with a serous fluid that protects the embryo or fetus and keeps it moist. See also chorion (Cf. ↑chorion). See picture under embryo. (Cf. ↑embryo)

╂[< Late Latin amnion < Greek amníon (diminutive) < amnós lamb]