Comment by ashdnazg

Fluent means different things to different people (and in different languages!).

As I understand it, B2 means one has a solid, functional proficiency in the language. They conversate/listen/read/write in diverse situations, without needing to switch to a different language or to prepare in advance.

They're very likely, however, to make mistakes, say things in non-idiomatic ways etc. although this is expected to be minor enough to not affect the ability to understand them.

In order to get to C1 and above, one needs a deeper understanding of the language - phrases, idioms, connotations, registers, etc. and a broader set of situations they can handle, e.g., a philosophical discussion. An of course, errors are expected to be rarer.

So, literally speaking, B2 is rather fluent, since the language is "flowing" out of them and they're not stopping to think every other word (which is, as far as I understand, a common interpretation of flüssig in German).

But as "fluent" speakers should know, words come with expectations beyond the literal meaning :P