[[File:|thumb|Fashions in muslin, 1838.]] Muslin is a type of finely-woven cotton fabric, introduced to Europe from the Middle East in the 17th century. It became very popular at the end of the 18th century in France. Muslin is most typically a closely-woven unbleached or white cloth, produced from corded cotton yarn. Wide muslin is called "sheeting". It is often used to make dresses or curtains but may also be used to complement foam for bench padding. Muslin breathes well, and is a good choice of material for clothing meant for hot, dry climates.
Muslin clothes were traded by ancient Greeks from the East Indian port town Masulipatam, known as Maisolos and Masalia in ancient times and the name 'Muslin' originated from the name Maisolos. Another view was that the fabric was named after the city where Europeans first encountered it, Mosul, in what is now Iraq, but the fabric actually originated from Dhaka in what is now Bangladesh. In the 9th century, an Arab merchant named Sulaiman makes note of the material's origin in Bengal (known as Ruhml in Arabic).
The word muslin is also used colloquially. In the United Kingdom, many sheer cotton fabrics are called muslin, while in the United States, muslin sometimes refers to a firm cloth for everyday use, which in the UK is known as calico.
[[File:|thumb|In Advantages of wearing Muslin Dresses! (1802), James Gillray caricatured a hazard of untreated muslin: its flammability.]]
When sewing clothing, a dressmaker may test the fit of a garment, using an inexpensive muslin fabric before cutting the intended expensive fabric, thereby avoiding potential costly mistakes. The muslin garment is often called a "muslin", and the process is called "making a muslin". With the availability of inexpensive synthetic fabrics, which closely resemble the hand (drape and feel) of expensive natural fabrics, a test or fitting garment made of synthetics may still be referred to as a muslin, because the word has become the generic term for a test or fitting garment.
Muslin can also be used as a filter in a funnel when decanting fine wine or port to prevent sediment from entering the decanter; and in cooking, is the material for the traditional cloth used when making a Christmas pudding. It is also used in the cheese making process to drain the curd.
Muslin is also often used as a backing or lining for quilts, and thus can often be found in wide widths in the quilting sections of fabric stores.
Muslin is often the cloth of choice for theater sets. It is helpful in masking the background of sets and helping to establish the mood or feel of different scenes. It can be painted to look like countless different settings, and if treated properly it can become semi-translucent.
It also holds dyes very well. It is often used to create night time scenes, because when it is dyed, it often gets a waved look with the color varying slightly such that it resembles a night sky. Muslin shrinks after it is painted, but it is widely used because it makes for a great paint surface.
In video production, muslin can also be used as a cheap bluescreen, either precolored or painted with latex paint (diluted with water).
Muslin is the most common backdrop material used by photographers for formal portrait backgrounds. It is usually painted, most often with an abstract mottled pattern.
In the early days of silent film making, up until the late 1920s, movie studios did not have the elaborate lights needed to illuminate indoor sets, so most interior scenes were sets built outdoors with large pieces of muslin hanging overhead to diffuse the lighting.
Muslin gauze has also found a use in cerebrovascular neurosurgery. It is wrapped circumferentially around aneurysms or intracranial vessels at risk for bleeding. The thought is that the gauze reinforces the artery and helps prevent rupture. It is often used for aneurysms that, due to their size or shape, cannot be microsurgically clipped or coiled. 
From Italian mussolina, from Mussolo (“‘Mosul’”) in Northern Iraq (cf. 1875 Knight, Edward H., Knight's American Mechanical Dictionary, V2 p1502: "Muslins are so called from Moussol in India.")
muslin (plural muslins)