What is a twill woven worsted fabric that has a diagonally ribbed surface called?

A twill woven worsted fabric that has a diagonally ribbed surface is called whipcord. Whipcord is specifically characterized by its distinct diagonal ribbing and is often made from worsted yarn, which contributes to its durability and thickness. This fabric is commonly used in garments such as trousers and outerwear, where its strength and unique texture can provide both aesthetic appeal and practical functionality.

Denim, while also a twill fabric, is typically associated with a specific type of cotton fabric known for its use in jeans and has a different texture and weight. Twill, as a term, refers broadly to the weaving pattern itself but does not denote any specific type of fabric. Satin, on the other hand, is known for its smooth and glossy finish rather than any ribbed texture, making it distinct from whipcord.