peri·​to·​ne·​um | \ ˌper-ə-tə-ˈnē-əm How to pronounce peritoneum (audio) \
plural peritoneums\ ˌper-​ə-​tə-​ˈnē-​əmz How to pronounce peritoneums (audio) \ or peritonea\ ˌper-​ə-​tə-​ˈnē-​ə How to pronounce peritonea (audio) \

Definition of peritoneum

: 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

Keep scrolling for more

Other Words from peritoneum

peritoneal \ ˌper-​ə-​tə-​ˈnē-​əl How to pronounce peritoneal (audio) \ adjective
peritoneally \ ˌper-​ə-​tə-​ˈnē-​ə-​lē How to pronounce peritoneally (audio) \ adverb

Examples of peritoneum in a Sentence

Recent Examples on the Web This is the first category because endometriosis often involves the peritoneum as a baseline characteristic. Cassie Shortsleeve, SELF, "What Exactly Are the Stages of Endometriosis?," 25 Sep. 2019 William Schaffner, a professor of medicine and infectious diseases at Vanderbilt University’s medical school, said another possibility is that an infection has spilled into the peritoneum, the lining of the abdomen. Washington Post, "HHS secretary readmitted to hospital for further treatment of diverticulitis," 18 Apr. 2018 Lynn told me that her husband, Mark, was diagnosed in September 2016 with late-stage cancer of the peritoneum, or abdominal lining. Lindsay Gellman, Longreads, "The Last Resort," 22 Mar. 2018 Cells can land on the uterosacral ligaments, uterus, fallopian tubes, ovaries, bowels, bladder, peritoneum, appendix, and sometimes in rare cases, the diaphragm, lungs, or the brain. Meghan Cleary, Teen Vogue, "Why Having A Hysterectomy to End Endometriosis Might Not Work," 14 Sep. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'peritoneum.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of peritoneum

15th century, in the meaning defined above

History and Etymology for peritoneum

Middle English, from Late Latin, from Greek peritonaion, neuter of peritonaios stretched around, from peri- + teinein to stretch — more at thin

Keep scrolling for more

Learn More about peritoneum

Time Traveler for peritoneum

Time Traveler

The first known use of peritoneum was in the 15th century

See more words from the same century

Statistics for peritoneum

Cite this Entry

“Peritoneum.” Dictionary, Merriam-Webster, Accessed 20 Feb. 2020.

Keep scrolling for more

More Definitions for peritoneum


variants: or chiefly British peritonaeum \ ˌper-​ət-​ᵊn-​ˈē-​əm How to pronounce peritonaeum (audio) \
plural peritoneums or chiefly British peritonaeums\ -​ˈē-​əmz How to pronounce peritonaeums (audio) \ or peritonea or chiefly British peritonaea\ -​ˈē-​ə How to pronounce peritonaea (audio) \

Medical Definition of peritoneum

: 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

More from Merriam-Webster on peritoneum Encyclopedia article about peritoneum

Comments on peritoneum

What made you want to look up peritoneum? Please tell us where you read or heard it (including the quote, if possible).


See Definitions and Examples »

Get Word of the Day daily email!

Test Your Vocabulary

More Confusing Words—Quiz

  • cats on impossible timber
  • The magician ______ moved the selected card to the top of the deck.
Spell It

Can you spell these 10 commonly misspelled words?

Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!