Grosgrain ( /ˈɡroʊɡreɪn/), also gros-grain and, rarely, gros grain, is a type of fabric characterized by its ribbed appearance. In grosgrain, the weft is heavier than the warp, creating prominent transverse ribs. It is called a "corded" fabric since the weft resembles a fine cord. Grosgrain is a plain weave corded fabric, with heavier cords than in poplin but lighter than in faille. Grosgrain has a very dull appearance with little luster but is very strong. It is a firm, close-woven, fine-corded fabric. While grosgrain fabric is generally black, it can be many different colors, and grosgrain ribbon comes in a large variety of colors and patterns.
As of 2010, “grosgrain” is commonly used to refer to a heavy, stiff ribbon of silk or nylon woven via taffeta weave using a heavy weft which results in distinct transverse ribs. Historically grosgrain was made from wool, silk or a combination of fibers such as silk and wool or silk and mohair. When a combination of fibers were used, the end result was sometimes given the name grogram, silk mohair, gros de Tours or gros de Napels.