<span>Is a large sheet of strong, flexible, water-resistant or </span><a href="https://en.wikipedia.org/wiki/Waterproof" class="mw-redirect" title="Waterproof">waterproof</a><span> material, often </span><a href="https://en.wikipedia.org/wiki/Cloth" class="mw-redirect" title="Cloth">cloth</a><span> such as </span><a href="https://en.wikipedia.org/wiki/Canvas" title="Canvas">canvas</a><span> or </span><a href="https://en.wikipedia.org/wiki/Polyester" title="Polyester">polyester</a><span> coated with </span><a href="https://en.wikipedia.org/wiki/Polyurethane" title="Polyurethane">polyurethane</a><span>, or made of <a href="https://en.wikipedia.org/wiki/Plastic" title="Plastic">plastics</a> such as <a href="https://en.wikipedia.org/wiki/Polyethylene" title="Polyethylene">polyethylene</a>.</span>