It's not a matter of making up definitions. It's a matter of you accepting that you like particular kind of open RPG. A game that allows the player to go off the beaten path is generally, by definition, an open world. Anywhere you can explore that is in no way necessary for the game is an open RPG. Mass Effect 2 and Dragon Age 2 are perfect examples of linear RPGs. The Witcher 2 is not, as there are plenty of large environments that the player is capable of exploring.
I disagree with you, perhaps the sites you visit use open in a way different than the site I do. Gamespot is the site I most often go to, followed by IGN and 1up.
I have not heard W2 refered to as an open world game(from online sites) nor based on what I read about it would I refer to it as such. But I don't want to argue over the def. W2 is NOT similar to Bethesda or Rock Star style open world games, were there is freedom to go wereever, back track,etc,etc. That is what I like, W2 is not that. I don't think W2 is a bad game because of it, its just not my type of game whatever you want to call it.
Now perhaps instead of trying to convince me its an open world game, you can try a different approach to get me to want to play W2, give me a link to details about the mod kit. Because I love mods. And I am asking because I thought I read there are releasing a mod kit for the game, I don't mean modding like the TW2 4 member mod community. I mean legit mod community because of a real mod kit.