Tweed: But, really, what is it?
noun || \ˈtwēd \
:: a rough woolen fabric made usually in twill weaves and used especially for suits and coats
Tweed originated in Scotland in the 18th century. Scottish weavers wished to make a denser and heavier cloth, and by developing the "twill" (the diagonal line running through the fabric) they produced what is recognized as tweed today. The generic term came from a London cloth merchant misreading "tweel", the Scottish version of twill. (Source: Independent.co.uk)