Per`i*to*ne"um (?), n. [L. peritoneum, peritonaeum, Gr. , , fr. to stretch all around or over; around + to stretch.] Anat.
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.
[Written also peritonaeum
© Webster 1913.