<p>That definition of fluent seems a little bit much to me.</p>
<p>My cousin, for example, is in his 50’s and has lived and worked in Italy for 30 years and would fit into your definition, I have been told by native speakers of Italian that you almost cannot tell that he is British when he speaks, which would fit that definition, yet it has taken him a few decades to achieve this; he also never had any formal training. </p>
<p>However, there are plenty of people who can speak a foreign language good enough to carry on an intelligent conversation but still may have a “thick” accent, which according to that definition they would not be fluent. I would consider someone fluent, if they can carry on a conversation with someone in any subject such as business/politics it should not matter that they do not have a “native” accent to be considered “fluent”.</p>