Abdomen

Anatomy, Zoology.

the part of the body of a mammal between the thorax and the pelvis; belly.
the cavity of this part of the body containing the stomach, intestines, etc.
(in nonmammalian vertebrates) a region of the body corresponding to, but not coincident with, this part or cavity.

Entomology. the posterior section of the body of an arthropod, behind the thorax or the cephalothorax.
Contemporary Examples

Prince Philip, 92, had an operation on his abdomen in June and spent 11 nights at the private London Clinic.
Prince Philip To Return To Public Life August 8, 2013

Defendant No. 1, who was 16 years old at the time, kicked Julani in the abdomen after he had fallen to the ground, said Zaban.
What If Israeli Would-Be-Lynchers Were Palestinians? Emily L. Hauser July 7, 2013

The man then pulled out a gun and shot the manager in the abdomen, police said.
Guns in the Home: Not as Safe as You’d Think David Frum March 18, 2013

Two bullets lodged in his abdomen and he was taken to the hospital for surgery.
The Man Syria’s Jihadists Want Dead Patrick Hilsman January 29, 2014

But even I have my share of patients with chronic pain of some kind, be it in the abdomen or head or back.
DEA’s Painkiller Crackdown Too Little, Too Late? Russell Saunders August 26, 2014

Historical Examples

Large specimens of the Robber Crab may be at least a foot in length of body when the abdomen is straightened out.
The Life of Crustacea William Thomas Calman

He received a bullet in the chest and another in the abdomen.
The Story of the Great War, Volume III (of VIII) Various

His abdomen also became distended so that he wore a bandage for comfort.
The Life of Ludwig van Beethoven, Volume III (of 3) Alexander Wheelock Thayer

He finished reading the paper in the warm, clear light of his abdomen.
The Velvet Glove Harry Harrison

The females (fig. 95) are straw-colored, the abdomen almost white, and the thorax and legs brownish yellow.
The Common Spiders of the United States James Henry Emerton

noun
the region of the body of a vertebrate that contains the viscera other than the heart and lungs. In mammals it is separated from the thorax by the diaphragm
the front or surface of this region; belly related adjective coeliac
(in arthropods) the posterior part of the body behind the thorax, consisting of up to ten similar segments
n.

1540s, “belly fat,” from Latin abdomen “belly,” of unknown origin, perhaps from abdere “conceal,” with a sense of “concealment of the viscera,” or else “what is concealed” by proper dress. De Vaan, however, finds this derivation “unfounded.” Purely anatomical sense is from 1610s. Zoological sense of “posterior division of the bodies of arthropods” first recorded 1788.

abdomen ab·do·men (āb’də-mən, āb-dō’mən)
n.
The part of the body that lies between the chest and the pelvis and encloses the stomach, intestines, liver, spleen, and pancreas. Also called belly, venter.
ab·dom’i·nal (āb-dŏm’ə-nəl) adj.
ab·dom’i·nal·ly adv.
abdomen
(āb’də-mən)

In vertebrates, the portion of the body between the thorax and pelvis, containing the stomach, intestines, liver, and other organs. In mammals, the abdomen is separated from the thorax by the diaphragm.

In arthropods, the last, most posterior segment of the body.

abdominal adjective (āb-dŏm’ə-nəl)
abdomen [(ab-duh-muhn, ab-doh-muhn)]

The part of the body between the thorax (chest) and pelvis that encloses the organs of the abdominal cavity; the belly.