Twill

A woven fabric, sometimes used in making clothing, with a surface of diagonal parallel ridges, produced by passing the weft threads over one and under two or more threads of the warp (instead of over and under in regular succession, which is how a lot of fabric is woven). (The warp threads on a weaving loom are those that are strung by the moving part of the loom; the weft are the threads at right angles to the warp.) The word “twill” can also refer to the characteristic appearance of such fabric and the process of making it (NSOED).