welt

• A finished edge on knit goods, especially hosiery. In women’s stockings, it is a wide band knitted from heavier yarn than the leg and folded on itself.
• In other applications, it is a small cord covered with fabric and sewn along a seam or border to add strength. A seam made by folding the fabric double, generally over a cord, and sewing it.
• Sometimes substituted for “pique.”

Source: Textile Glossary by Marvin Klapper
Category: Fiber