abdomen

noun4

1. •
   The belly, or that part of the body between the thorax and the pelvis, not including the back; or in some lower vertebrates, the portion between the cardiac and caudal regions.
2. •
   The cavity of the belly, which is lined by the peritoneum, and contains the viscera; often restricted in humans to the part between the diaphragm and the commencement of the pelvis, the remainder being called the pelvic cavity.

   • He was all bent over complaining of pains in the abdomen.
3. •
   The posterior section of the body, behind the thorax, in insects, crustaceans, and other Arthropoda.
4. •
   (no longer used) The fat surrounding the belly.