in weaving, any yarn running across the width of the fabric perpendicular to the warp yarns. In woven carpet, filling yarns are part of the group of construction yarns which also include chain and stuffer warp and form the backing. Woven carpet fill and chain warp yarns interface to secure the pile yarns. Filling and other construction yarns usually are fibrillated polypropylene, jute, kraftcord, or similar materials.
