Corduroy is a woven fabric with cord-like fibers (wales) usually running with the selvedge. These fibers also have a nap to them, so keep that in mind when cutting out your pattern. Corduroy can be found in a variety of weights - lightweight for shirts and childrenswear and medium-heavy weight for pants, jackets, skirts and dresses. The size of the wales (cords) can vary from pinwale (tiny) to wide wale (large) and all sizes in between.
Fun Fact! How is the wale name determined? Count how many wales in are in one inch. 12-wale corduroy = 12 wales in one inch!