Piracy isn't stealing. You don't go to the store and take the CD off the shelf. You are merely copying data that has been uploaded to the internet.
In fact, the real difference between piracy and stealing is exactly what zz_tophat said, piracy is copying, not taking. You cannot call someone who stole a CD from a store a pirate (Unless of course they were pillaging your town, but in most instances this is not the case), just as you cannot call someone who copies data a thief.
Or yet another way to say it, IMPLIED MEANING.
It isn't implied if it says it in the dictionary.