The question of the definition of fluency has been beat to death over the years at HTLAL. But this is a new forum and it hasn't (yet) been flogged here. So let's have it! Three words stick out for me from the debates on the other forum: fluent, fluid and proficient. And then of course there are the 4+1 competencies: the active ones of speaking and writing, and the passive ones of listening and reading. Plus some researchers add another one that is an enhanced listening comprehension: the ability to follow the course of an ordinary conversation among native speakers. To me, fluency = fluidity + proficiency across all 4+1 competencies. Anything less requires at least one, and most likely more, modifiers. And by proficiency, at least for reading, I go by the lexical threshold which =15,000+ word vocabulary, at least for English. Those who advocate that one can be fluent with only 3K words, really only can claim one can in speaking fluidly use those words in highly constrained/ideal conditions, namely: the the conversation goes into no real depth, one uses frequent and often awkward circumlocutions, and one gets to guide the conversation. So they might be fluid, but lacking any degree of proficiency by educated standards, they are merely fluid across a restricted scope of the language. While it is true that virtually no one would claim that say a native speaker with only a grade school education is not fluent, in reality that person's use of his/her own language is constrained by a lack of full proficiency, despite the fact it may be perfectly adequate for customary daily needs and interactions. Too many course designers and language teachers have sought to advocate for a restricted definition of fluency to support their own financial interests. And all the anecdotal "evidence" stories in the world don't overcome research which supports the necessity of having a much larger vocabulary for both listening and reading comprehension. After all, if you can't comprehend native speakers and native written materials, then again you can only claim some modified level of fluency, regardless of how fluidly you might use the little vocabulary that you know. Anyway, that's my, perhaps not quite so humble, and likely contentious, opinion.