Boiled wool is a special type of fabric primarily used in berets, scarves, vests, cardigans, coats and jackets. It is created using a mechanical knitting process which involves a set pattern that is then shrunk. It can also be a woven fabric which is shrunk, compressing the fibres together.

Wool felt and felted wool are similar to boiled wool, all of these processes date back to at least the Middle Ages. The word felt itself comes from West Germanic feltaz.

Wool felt can be created commercially and results in uniform fabric thickness. This dense wool is created by first weaving wool to create an item then washing it, resulting in a solid, dense fabric that is about 30% smaller than the original woven material. This process is called "fulling", as opposed to felting, which is a non-woven fabric. Boiled wool is produced industrially and is characteristically found in Tyrolean textiles of Austria and of South America.

Very large woven sheets of wool fabric are first either dyed or not, with a design on them. These are boiled and shrunk without using any chemicals. Because of this and other factors, boiled wool is a tight knit fabric, very warm, windproof and usually does not itch.