decidua

de·cid·ua

noun \di-ˈsij-ə-wə\

plural de·cid·uae \-ˌwē\

Definition of DECIDUA

1

: the part of the mucous membrane lining the uterus that in higher placental mammals undergoes special modifications in preparation for and during pregnancy and is cast off at parturition, being made up in the human of a part lining the uterus, a part enveloping the embryo, and a part participating with the chorion in the formation of the placenta—see decidua basalis, decidua capsularis, decidua parietalis

2

: the mucous membrane of the uterus cast off in the ordinary process of menstruation

—de·cid·u·al \-ə-wəl\ adjective