The waist is the part of the abdomen between the ribcage and hips. On some people, the waist is the narrowest part of the torso.
Waistline refers to the horizontal line where the waist is narrowest, or to the general appearance of the waist. People who diet are often said to be trying to "improve" their waistline.
The waistline of clothing generally corresponds to the human waist.
Traditionally belts are worn around the waist.
Jewelry, such as a belly chain, may be worn around the waist.
Waist reduction may be used simply to reduce the width of the waist. This change can be permanent or temporary.
Waist training may be used to achieve a certain permanent waist shape, such as a pipe-stem waist.