The original British title is "Philosopher's Stone." (I'll let someone with more knowledge here explain how the Philosopher's Stone is an actual historical legend, or however you want to put it.) For the American market, the title was changed to "Sorcerer's Stone," presumably because American kids wouldn't know the history of the Philosopher's Stone anyway, and "Sorcerer's" would sell more books. (Remember, this was Book 1, before Harry was an international phenomenon.)