Noun, pl. endometria
1. The inner mucous membrane of the mammalian uterus. (wikipedia.org)
2. The mucous membrane that lines the uterus in mammals and in which fertilized eggs are implanted. (wiktionary.org)
4. The mucous membrane lining the uterus, which thickens during the menstrual cycle in preparation for possible implantation of an embryo. (Google Dictionary)
5. The mucous membrane that lines the uterus; thickens under hormonal control and (if pregnancy does not occur) is shed in menstruation; if pregnancy occurs it is shed along with the placenta at parturition. (wordnetweb.princeton.edu)
Word origin: From endo- (“inner”) + Late Latin metrium (“womb”), from Ancient Greek μήτριον (“of a mother”).