Main Entry: am·ni·on

Pronunciation: \ˈam-nē-ˌän, -ən\

Function: noun

Inflected Form(s): plural amnions or am·nia \-nē-ə\

Etymology: New Latin, from Greek, caul, from amnos lamb — more at yean

Date: 1667

1 : a thin membrane forming a closed sac about the embryos or fetuses of reptiles, birds, and mammals and containing the amniotic fluid
2 : a membrane analogous to the amnion and occurring in various invertebrates

— am·ni·ot·ic \ˌam-nē-ˈä-tik\ adjective