Decidua

from WordNet (r) 3.0 (2006)

decidua
    n 1: the epithelial tissue of the endometrium

from The Collaborative International Dictionary of English v.0.48

Decidua \De*cid"u*a\ (?; 135), n. [NL., fr. L. deciduus. See
   {Deciduous}.] (Anat.)
   The inner layer of the wall of the uterus, which envelops the
   embryo, forms a part of the placenta, and is discharged with
   it.
   [1913 Webster]