Peritoneum
Peritoneum , noun
[Latin peritoneum, peritonaeum, Greek {not transcribed}, {not transcribed}, from {not transcribed} to stretch all around or over; peri` around + {not transcribed} to stretch.]
(Anatomy) The smooth serous membrane which lines the cavity of the abdomen, or the whole body cavity when there is no diaphragm, and, turning back, surrounds the viscera, forming a closed, or nearly closed, sac.