twill, one of the three basic textile weaves, producing a fabric with a diagonal rib, ridge, or wale. In regular twill the diagonal line is repeated regularly, usually running upward from left to right at a 45° angle.
The weave can be varied in many ways, for example, by changing the direction of the twill line (as in herringbone twill) or its angle. The smallest twill is one of the most popular weaves in men’s wear.