/ ˌperɪtəˈniəm; NAmE / noun
( pl. peri·ton·eums or peri·ton·ea / -ˈniə; NAmE /) ( anatomy ) the membrane (= very thin layer of tissue ) on the inside of the abdomen that covers the stomach and other organs
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WORD ORIGIN
late Middle English : via late Latin from Greek peritonaion , from peritonos stretched round, from peri- around + -tonos stretched.