Lambswool is the wool of a lamb that has been shorn within the first six to twelve months of life. It is only at this age that the required length of the long pile is reached, which can be used for further processing. This comes from the very first shearing. Normally shearing is done at the beginning of summer at the earliest, as otherwise free-living sheep would suffer from the cold in winter.

It is particularly fine and soft, which means that it hardly scratches the skin at all. Lambwool can be recognised under the microscope by the presence of the rounded hair tips. However, compared to the wool of older sheep, it is not as durable or strong.