Well, the definition of fluency varies a lot from people to people, including linguists. But the strict definition of the term is "when language flows", it says nothing about grammatical mistakes. As long as the speaker isn't hesitant and is understood by natives, s/he's considered fluent by this definition.
Well, the definition of fluency varies a lot from people to people, including linguists. But the strict definition of the term is "when language flows", it says nothing about grammatical mistakes. As long as the speaker isn't hesitant and is understood by natives, s/he's considered fluent by this definition.
See this wikipedia article about language proficiency.