I can really answer this question in the most general way fulfilling its general definition and telling you that am able to speak two different languages and can speak them fluently.
Yet this answer wouldn’t satisfy me at all. I’m not saying that it is a false statement, but it is not entirely true either. I am a bilingual person, I can speak English and Spanish, whenever the occasion calls for it. I am able to understand, read and write. But oftentimes, I find myself questioning particular words, those that I don’t come across so often. So in these cases, I find myself being less fluent, it can even become an impediment to communicate with. Therefore I am not entirely articulate in terms of being able to use the appropriate words at times, at the appropriate setting (although I do keep watch of where I am at) and so on. But there is another type of language I am completely convinced I master. The one at home, with friends, and with myself. It is not to say that I start speaking gibberish all of the sudden. But that more about the language that involves the Spanglish at home, the casual talk with your friends, or the one that you have when no one is around. It is the type of language that involves a different setting, of course, but I guess it’s safe to say it is my first language. Where regardless of the grammatical mistakes or using a wrong word in place of another, everybody (whom you’re used to being around with) understands you. This is where I find myself the most articulate of all, to the full extent of the word.