Filament thread is a strong sewing thread made from long, continuous strands (filaments) of synthetic fibers like polyester or nylon, creating a smooth, shiny, and durable thread, distinct from spun threads made of short fibers; it comes in types like single-strand monofilament (stiff, for hems) and multi-strand multifilament (twisted for high strength in shoes, upholstery) and textured versions for stretch/cover stitches, offering high tenacity for industrial use.