Toboggan: hat or sled?

It's that age-old bafflement: the word "toboggan" -- is it a hat or a sled? And how in the world did this noun come to describe two such varied objects? Is it a coincidence that they both have to do with winter?

And I challenge you to present me with another word that serves the function of descriptive noun for two VERY different objects. I cannot think of one.

So which is it to you, a sled or a hat?