This section is from the "A Complete Dictionary of Dry Goods" book, by George S. Cole. Also available from Amazon: A complete dictionary of dry goods and history of silk, cotton, linen, wool and other fibrous substances,: Including a full explanation of the modern processes ... together with various useful tables.
Tweed. A woolen cloth manufactured solely for men's clothing. It is a twilled fabric, two or more colors being generally combined in one yarn, and of soft, open and flexible structure. On leaving the loom, tweeds are slightly fulled, teasled, and the fibrous nap so raised sheared down smooth, and then pressed. The object of these operations is to make the pattern appear more prominent and clearly defined. When first manufactured the patterns of tweeds were confined to shepherd checks of three or four sizes. After the original style of tweed had enjoyed popularity for several years, it happened that an English manufacturer had made up a quantity of these checks in which the whites were so impure and dirty looking, from being mixed with inferior wool, that they would not sell. The happy idea struck him that if the pieces were dipped in a brown dye it would cover the white and convert the checks into brown and black. This was managed so successfully that upon these "new styles" being sent to London they not only sold rapidly, but large orders flowed in for more in all the different sizes of checks. To this circumstance is attributed the beginning of the manufacture of "fancy tweed." At present the fabric is woven in all descriptions of checks and stripes, as well as plain styles. Tweeds were for many years called "twills." The Scotch people pronounce the word twill as "tweel." It was the word "tweels" having been blotted or imperfectly written in an invoice which gave rise to the now familiar name of these goods. In a certain lawsuit the word was read "tweeds" by the late James Lock, of London, and it was so appropriate from the fact of the goods being almost exclusively made on the banks of River Tweed, Scotland, that it was at once adopted, and has been continued ever since.