Definition of "peritoneum" [per•i•to•ne•um]

• The serous membrane that lines the walls of the abdominal cavity and folds inward to enclose the viscera. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The peritoneum is the mesothelial tissue that covers most of the organs in the abdominal cavity."
• "The under surface is covered by peritoneum, which is reflected on to it from the surface of the liver."
• "The spleen is almost entirely surrounded by peritoneum, which is firmly adherent to its capsule."