Woolen (American English) or woollen (British English and Canadian English) is a type of yarn made from carded wool. Woolen yarn is soft, light, stretchy, and full of air. It is thus a good insulator, and makes a good knitting yarn. Woolen yarn is in contrast to worsted yarn, in which the fibers are combed to lie parallel rather than carded, producing a hard, strong yarn.

The woolen and worsted process both require that the wool (and other similar animal fibers, cashmere, camel, etc.) are cleaned before mechanical processing. Woolen and worsted nomenclatures apply only to the textile processing of animal fibers, but it has become common to include fiber blends under these terms.

The resultant fabrics will be classified as being either woolen or worsted, but this designation is assigned during fiber processing and yarn formation, not in the cloth or finished garment.

A woven woolen fabric is one which is subjected to fabric finishing techniques designed to add a directional pile - in that the end consumer can 'stroke' the garment in a single direction (shoulder to cuff etc.), such as a casual jacket. This feels like the fibers are directionally arranged.