Sorry to
deflate your bubble, but
anime is the Japanese word for Cartoon in the sense in which it is often used in English, i.e. any kind of movie that is animated.
Disney movies are called anime in Japan, and placed right next to the domestic animated products.
As for the "compelling art medium", this is a minority view in Japan nearly as much as in the West, the view of fans and those in the industry. Most people consider anime kids' stuff, something you grow out of. Seiyuu are celebrities, but only to a relatively small circle of fans. Megumi Hayashibara of all people complained (in an interview that I read recently, but which I can't find anymore) that people were not taking her work seriously because she voiced anime, and that this was changing somewhat only recently.
Sure, there is a noticeable difference: the number of fans, of otaku, is of course much larger in Japan, and everyone is a bit more willing to concede exceptions to the norm and admit a lasting fondness for their own childhood favourites, but by and large, anime is most certainly not considered a medium for adults.