What is Waist?
Waist is (noun) 1. the narrower part of the body between the bottom of the chest and the hips She measures 32 inches round the waist or has a 32-inch waist. 2. the part of a piece of clothing, e.g. a skirt, trousers or dress, that goes round the middle of your body The waist of these trousers is too small for me. (NOTE: Do not confuse with waste.)
source: Easier English, Student Dictionary Upper Intermediate Level