What is "peritonaeum"

Peritoneum \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 periton[ae]um.]

n. (alternative form of peritoneum English)