sailcloth

Originally, a firmly woven cotton canvas used for making sails. Today, sailcloth is a very heavy, strong, plain-weave fabric made of cotton, linen, jute, nylon, or palyester. It comes in many qualities and weights. In common usage, the terms duck, sailcloth, and canvas often are used interchangeably. Sailcloth can be used for sportswear, slipcovers and upholstery, and curtains and draperies. See canvas and duck.