waistline

(wāstˈlīnˌ)

1. a. A line thought of as encircling the body at the waist.
   b. The measurement of this line.
2. a. The point or line at which the skirt and bodice of a dress join.
   b. The part of a garment that covers the narrowest part of the waist or the part above or below it as the current fashion demands.