Shaggy describes something covered with long, rough, or tangled hair or fibers. A shaggy dog has a thick, untrimmed coat that hangs loosely and might look a bit messy, like an Old English Sheepdog whose fur covers even its eyes. A shaggy carpet has long, deep fibers that feel soft underfoot but might show every footprint.

The word suggests a certain wildness or lack of grooming. Someone with shaggy hair hasn't had a haircut in a while, so their hair hangs unevenly over their ears and collar. A shaggy lawn needs mowing because the grass has grown tall and uneven. There's often something cozy or comfortable about shagginess: shaggy sweaters, shaggy rugs, and shaggy animals can have a soft, touchable quality that smooth or neat things don't.

You might also hear about a shaggy dog story, which is a long, rambling joke that goes on and on with lots of irrelevant details before reaching a disappointing or silly punchline. The story itself is “shaggy” because it's messy and overgrown, just like that untrimmed dog.