peritoneum
noun
peri·to·ne·um
ˌper-ə-tə-ˈnē-əm 
plural peritoneums
ˌper-ə-tə-ˈnē-əmz
or peritonea
ˌper-ə-tə-ˈnē-ə
or peritonea
ˌper-ə-tə-ˈnē-ə
: the smooth transparent serous membrane that lines the cavity of the abdomen of a mammal and is folded inward over the abdominal and pelvic viscera
Examples of peritoneum in a Sentence
Recent Examples on the Web
This area contains the peritoneum, a thin layer of tissue that lines the abdominal wall and covers the organs.
—
Julie Scott, Msn, Anp-Bc, People.com, 28 Feb. 2025
In stage 4c, rectal cancer has spread to the abdominal wall lining (peritoneum).
—Corey Whelan, Verywell Health, 15 Aug. 2024
Somatic pain: This pain usually comes from irritation of the peritoneum, the protective lining of the abdominal cavity.
—Lindsay Curtis, Health, 10 July 2024
Normally this causes fever and abdominal pain that is initially felt in the region around the belly button but then moves to the right lower quadrant as the infection and inflammation spread to the highly sensitive lining of the abdominal cavity known as the peritoneum.
—Lisa Sanders, M.d., New York Times, 10 Jan. 2024
What’s under it is the same as what’s under the skin of the rest of your abdomen: your abdominal muscles, to which the navel is attached by a short umbilical stalk, and the peritoneum, the membrane that lines the abdominal cavity.
—Sarah Leupen, The Conversation, 5 Apr. 2023
Peritoneal dialysis uses the peritoneum, the lining of the abdomen, which contains the organs, to mimic a kidney by using large amounts of fluid inside the peritoneum to absorb wastes without needing to remove the blood from the body.
—Dr. Keith Roach, oregonlive, 9 Feb. 2022
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Julie Scott, Msn, Anp-Bc, People.com, 28 Feb. 2025
In stage 4c, rectal cancer has spread to the abdominal wall lining (peritoneum).
—Corey Whelan, Verywell Health, 15 Aug. 2024
Somatic pain: This pain usually comes from irritation of the peritoneum, the protective lining of the abdominal cavity.
—Lindsay Curtis, Health, 10 July 2024
Normally this causes fever and abdominal pain that is initially felt in the region around the belly button but then moves to the right lower quadrant as the infection and inflammation spread to the highly sensitive lining of the abdominal cavity known as the peritoneum.
—Lisa Sanders, M.d., New York Times, 10 Jan. 2024
What’s under it is the same as what’s under the skin of the rest of your abdomen: your abdominal muscles, to which the navel is attached by a short umbilical stalk, and the peritoneum, the membrane that lines the abdominal cavity.
—Sarah Leupen, The Conversation, 5 Apr. 2023
Peritoneal dialysis uses the peritoneum, the lining of the abdomen, which contains the organs, to mimic a kidney by using large amounts of fluid inside the peritoneum to absorb wastes without needing to remove the blood from the body.
—Dr. Keith Roach, oregonlive, 9 Feb. 2022
Cite this Entry
“Peritoneum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/peritoneum. Accessed 31 Oct. 2025.
Copy CitationKids Definition
peritoneum
noun
peri·to·ne·um
ˌper-ət-ᵊn-ˈē-əm
plural peritoneums or peritonea
-ˈnē-ə
: the smooth transparent membrane that lines the cavity of the abdomen and encloses the abdominal and pelvic organs
Medical Definition
peritoneum
noun
peri·to·ne·um
variants
or chiefly British peritonaeum
: the smooth transparent serous membrane that lines the cavity of the abdomen of a mammal, is folded inward over the abdominal and pelvic viscera, and consists of an outer layer closely adherent to the walls of the abdomen and an inner layer that folds to invest the viscera see parietal peritoneum, visceral peritoneum compare mesentery sense 1
Love words? Need even more definitions?
Merriam-Webster unabridged
Share