waistline

noun
  1. 1

    A line around the body at the waist; its measurement

  2. 2

    The narrowest part of a garment, usually at the waist, but may be above or below depending on the dictates of fashion or the whim of the designer

  3. 3

    Person having a large waistline

Synonyms

Source: https://en.wiktionary.org/wiki/waistline