Its a pretty rambling post, but it does address the semantic issue of "fluency". I think fluency is when you can speak with someone in that country comfortably

Its a pretty rambling post, but it does address the semantic issue of "fluency". I think fluency is when you can speak with someone in that country comfortably. The rest is just qualification: pretty/reasonably/quite/very fluent. One can also be fluent in speaking, but not so much at reading or writing (mostly writing).