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
2.
the front or surface of this region; bellyRelated: coeliac
3.
(in arthropods) the posterior part of the body behind the thorax, consisting of up to ten similar segments
1550s, from medical L. abdominalis, from abdomen (see abdomen). Abdominals short for "abdominal muscles" attested by 1980; colloquial shortening abs is attested by 1992.
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.