What's the "een" in Halloween?
peritoneum per·i·to·ne·um or per·i·to·nae·um (pěr'ĭ-tn-ē'əm)
n. pl. per·i·to·ne·a or per·i·to·nae·a (-tn-ē'ə)
The serous sac consisting of mesothelium and a thin layer of irregular connective tissue that lines the abdominal cavity, covers most of the viscera contained therein, and itself forms two cavities, the peritoneal and the omental bursa, which are connected by the epiploic foramen.
The membrane that lines the walls of the abdomen and the pelvis (called the parietal peritoneum) and encloses the abdominal and pelvic organs (called the visceral peritoneum.) The space between the two, the peritoneal cavity, fills with inflammatory cells and pus when the peritoneum becomes infected.
large membrane in the abdominal cavity that connects and supports internal organs. It is composed of many folds that pass between or around the various organs. Two folds are of primary importance: the omentum, which hangs in front of the stomach and intestine; and the mesentery, which attaches the small intestine and much of the large intestine to the posterior abdominal cavity.