OC = Original Character. It applies whether or not in a fandom RP when you create your own character that has their own name, ideals, and abilities, separate and distinct of those of their compatriots, or, in the case of fandom, the characters whom canonically exist.

Everything else is moot. It doesn't matter if your character is a talking tea pot or a master of the universe, if (s)he is their own distinct entity and not "Alladin as a tea pot" or otherwise, you've probably got an OC. If the character is literally Naruto, then you're not playing an OC.

Clear 'nuff?