Noil is the short fiber

Fiber

Fiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....

 left over from combing

Combing

Combing is a method for preparing carded fibre for spinning. It separates out the short fibres by means of a rotating ring of steel pins. The fibres in the 'top' it produces, have been straightened and lie parallel to each other...

 wool

Wool

Wool is the textile fiber obtained from sheep and certain other animals, including cashmere from goats, mohair from goats, qiviut from muskoxen, vicuña, alpaca, camel from animals in the camel family, and angora from rabbits....

 or spinning

Spinning (textiles)

Spinning is a major industry. It is part of the textile manufacturing process where three types of fibre are converted into yarn, then fabric, then textiles. The textiles are then fabricated into clothes or other artifacts. There are three industrial processes available to spin yarn, and a...

 silk

Silk

Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...

 and used as a decorative additive for many spinning projects, like rovings

Roving

A roving is a long and narrow bundle of fibre. It is usually used to spin woollen yarn. A roving can be created by carding the fibre, and it is then drawn into long strips. Because it is carded, the fibres are not parallel, though drawing it into strips may line the fibres up a bit...

 and yarns

Yarn

Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knitting, weaving, embroidery and ropemaking. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or...

. Silk noil is also called "raw silk", although that is a misnomer

Misnomer

A misnomer is a term which suggests an interpretation that is known to be untrue. Such incorrect terms sometimes derive their names because of the form, action, or origin of the subject becoming named popularly or widely referenced—long before their true natures were known.- Sources of misnomers...

. As noil is a relatively short fiber, fabric made from noil is weaker and considered less valuable.

The plural noils is also used, and means the same as noil.