I think this runs into an important problem of trying to overly formalise categories, which makes sense for medical usage, but just leads to pedantry in most ca

I think this runs into an important problem of trying to overly formalise categories, which makes sense for medical usage, but just leads to pedantry in most cases. If some one feels "addicted" to some thing, and almost anyone would agree that they at least seem to be so, it's of no use to say "well technically, addiction requires these conditions and must be verified by this test". There's a similar thing with depression, where people will try discredit others by implying their depression isn't real because it hasn't been diagnosed and confirmed by a doctor. If you're really damn sad for a really long time, our word for that is depression. If medicine wants to use the same word to describe a similar-but-more-precise condition, they can feel free. But most of the time we're not talking in a medical context.