Peritoneum

from WordNet (r) 3.0 (2006)

peritoneum
    n 1: a transparent membrane that lines the abdominal cavity in
         mammals and covers most of the viscera

from The Collaborative International Dictionary of English v.0.48

Peritoneum \Per`i*to*ne"um\, n. [L. peritoneum, peritonaeum, Gr.
   ?, ?, fr. ? to stretch all around or over; peri` 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}.]
   [1913 Webster]