Pronunciation: (un'dur-bel"ē),[key] —n., —pl.-lies. 1. the lower abdomen; posterior ventral area, as of an animal's body.
2. the lower surface of an object; underside: the underbelly of an airplane. 3. a vulnerable area; weak point: an attack on the soft underbelly of Europe. 4. a dark, seamy, often hidden area or side: a police officer continually exposed to the underbelly of society.