Twill is a weave that is used in making many kinds of strong, durable cloth. In twill, the lengthwise threads, known as warp, meet the crosswise threads, called weft or filling, in such a way that diagonal lines form on the surface of the finished cloth in the areas where the yarns interlace. These diagonal lines may slant to the left or the right. They may be raised a little or a great deal. Many twill fabrics display an even number of warp and weft yarns on the surface, but some show more of one type than the other. Twill weaves can be varied to produce broken, entwining, figured, or reversing lines. Such materials as serge, gabardine, denim, and cheviot are twill-weave fabrics.
