Multilingualism

There are countless definitions of multilingualism and linguists are still debating which one is the most accurate. Here is a very simple on: multilingualism is an ability to use multiple languages by an individual speaker. Is that so? If someone speaks basic or intermediate  French and Italian does it make him/her a multilingual person? I don't think so. For me the knowledge of the language should be complete. But then again what does it mean? When are you fluent in a language? Where is the border? Impossible to say...