A gusset's a device, often triangular, used to reinforce a connection between two components. Gussets are commonly used in engineering, sewing and armour. Sewing In sewing, a gusset's a triangular or square piece of fabric inserted into a seam to add breadth or reduce stress. Gussets were used at the shoulders, underarms, and hems of traditional shirts and chemises made of rectangular lengths of linen to shape the garments to the body. Gussets are used in manufacturing of modern tights or pantyh… (More on Gusset)