A figure-eight-shaped ukulele has two bulges that are called bouts. Other shapes, such as banjo, pineapple, or teardrop, have no bouts.
The upper bout starts at the neck joint below the neck. Many ukuleles have their sound hole in the upper bout.
The lower bout marks the bottom end of the body.
The waist is the indentation between upper bout and lower bout. Banjo, pineapple or teardrop shaped ukuleles have no waist.