intractable problem example? I have been doing some research into the limits of computation and I have come across the terms intractable and undecidable. Are these two terms the same thing?

What does intractable mean and what is an example of an intractable and undecidable problem?
Tractable usually means decidable in polynomial time.  Under that definition, NP-complete problems appear to be intractable, but they're still decidable.