Tweed is a rough, woollen fabric, of a soft, open, flexible texture, resembling cheviot or homespun, but more closely woven. It is usually woven with a plain weave, twill or herringbone structure. Colour effects in the yarn may be obtained by mixing dyed wool before it is spun.

Tweeds are an icon of traditional Scottish, Irish, Welsh and English clothing, being desirable for informal outerwear, due to the material being moisture-resistant and durable. Tweeds are made to withstand harsh climates and are commonly worn for outdoor activities such as shooting and hunting, in England, Wales, Ireland and Scotland. In Ireland, tweed manufacturing is now most associated with County Donegal but originally covered the whole country. In Scotland, tweed manufacturing is most associated with the Isle of Harris in the Hebrides.