Originally Posted by Ken G

Are you talking about the professional definition of a planet? If you think that has been clear for a hundred years, you'd have to go with the one that includes minor planets as planets. I would tend to think even the professional definition has always been murky on that, depending on who you ask. I would rather believe that the professional definition (as distinguished from popular media) has always included minor planets as planets, but if that were true the IAU would have gone a different way.