Tweed is a rough, durable wool fabric with a distinctive texture, woven in patterns that mix different colored threads. If you've seen a jacket that looks nubby and textured, with flecks of brown, gray, or green woven together, you've probably seen tweed. The fabric originated in Scotland and became famous in the cold, rainy Scottish Highlands, where shepherds and farmers needed warm clothing that could stand up to harsh weather.

Tweed is surprisingly tough: it resists wind and light rain, and it actually gets better with age rather than wearing out quickly. The mixed colors in tweed help hide dirt and stains, which made it perfect for people working outdoors. English aristocrats adopted tweed for hunting and shooting on their country estates, and it became associated with professors, detectives in old mystery novels, and anyone who wanted to look scholarly or outdoorsy.

Today, tweed appears in jackets, caps, and even bags. The word can also describe something that has that rough, traditional, academic feeling. You might hear someone described as tweedy if they seem bookish and old-fashioned, like they'd be comfortable in a library surrounded by leather-bound books.