Noun, pl. abdomens or abdomina
1. In vertebrates such as mammals, constitutes the part of the body between the thorax (chest) and pelvis. (wikipedia.org)
2. The region of the body in between the thorax and the pelvis. (biology-online.org)
4. The posterior part of the body of an arthropod, esp. the segments of an insect’s body behind the thorax. (Google dictionary)
Word origin: From Latin abdōmen.