Definition of "Belly" :

noun: the underpart of the body of certain vertebrates such as snakes or fish

noun: a protruding abdomen

noun: the region of the body of a vertebrate between the thorax and the pelvis

noun: the hollow inside of something

"In the belly of the ship."

noun: a part that bulges deeply

"The belly of a sail."

verb: swell out or bulge out