A long strap made of leather, webbing, or heavy fabric worn around the waist or hips. It threads through loops on trousers or skirts to adjust the fit and prevent the garment from slipping down. It is also used externally over dresses and coats to define the waistline and control the drape of the fabric.
Heard on the job
Thread the belt through all the loops before you put the trousers on the mannequin.