Tweed is a rough, coarse, unfinished woollen fabric, of a soft, open, flexible texture resembling cheviot or homespun, but more closely woven. It is made in either plain or twill weave and may have a check or herringbone pattern. Subdued, interesting color effects (heather mixtures) are obtained by twisting together differently coloured woolen strands into a two- or three-ply yarn.

Tweeds are desirable for informal outerwear, being moisture-resistant and durable. Once worn in, tweeds are commonly worn for outdoor activities such as shooting and hunting, in both Ireland and the United Kingdom.