Where can I find the definitions of the fluency levels?
I am "52 % fluent" in Spanish yet I have no idea what that means. Where are these definitions listed?
Here is the announcement page. According to it:
[Fluency] is calculated based on what words you know, how important those words are, how well you know them, and how likely you are to forget them. It will increase over time as you learn more words and strengthen your skills, but it will decrease if you don't keep up your strength. Since our goal is for this estimate to be as accurate as possible, be aware that finishing your tree won't get you to 100%