Animal fibre other than sheep’s wool or silk.
Note:It is recognized that this definition implies a distinction between sheep’s wool and the covering of other animals, notwithstanding the similarity in their fibre characteristics. Thus the crimped form and the scaly surface are not confined to sheep’s wool. It seems desirable in the textile industry, however, to avoid ambiguity by confining the term wool to the covering or sheep and to have available a general term for other fibres of animal origin. Normally the less widely used fibres are known by name e.g., alpaca, mohair, etc., but collectively they should be classed as hair. A difficulty arises when it is desired to distinguish between the fibres of the undercoat and the remainder of the fleece; for instance, between the soft short camel hair used for blankets and the coarse long camel hair used for belting. The term wool is sometimes used for the shorter fibre, qualified by the name of the animal, e.g., cashmere wool
Textile Resource (http://www.textile.org.uk)