Corduroy is a fabric composed of twisted fibers lying parallel to another called cord. The width between the cords is usually name wale. It used to made of cotton; today it mostly tufted cords are used but also other fabrics like polyester or rayon.
The word corduroy itself is supposed to be derived from the French corde du roi, which means cord/cloth of the king. However, it is believed that the fabric was first produced in Manchester, England. Occasionally corduroy trousers are also called Manchester trousers, for example in German.
Apart from casual clothing, like jackets and trousers, corduroy is also used for shoes, bags, upholstery and others.
sources: Wikipedia and Wisegeek
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