am·ni·on (ām'nē-ən, -ŏn') n.
pl.am·ni·ons or am·ni·a (-nē-ə) A thin, tough, membranous sac that encloses the embryo or fetus of a mammal, bird, or reptile. It is filled with a serous fluid in which the embryo is suspended.
Main Entry: am·ni·ot·ic Pronunciation: "am-nE-'ät-ik Function: adjective 1: of or relating to the amnion 2: characterized by the development of an amnion