waistlineEnglishOxford Dictionary of Englishwaistline /ˈweɪs(t)lʌɪn / ▸ noun 1 the measurement around a person's body at the waist: eliminating inches from the waistline. ▪ the shaping and position of the waist of a garment: the changing waistline in women's fashions. 2 an imaginary line around a car or other vehicle at the level of the bottom of the windows.