Language works how it works. It doesn't matter for original definition because a lot of the words we use today were not even "originally" words. First a word is created or a word is used out of context in a slang way. The slang becomes common speech among people. The speech becomes recognized enough that it becomes a part of culture. The dictionary is not used to dictate our language, but is used as an accommodation to such. If a word becomes used enough in a certain way, that definition makes its way into our expectations of that word. In this way, a virgin can be someone who is penetrated by a penis, or it can be someone who hasn't had sex, the same way that the common phrase "piss off" means leave. Pretending that phrase is nonsensical is not only idiotic, but is close minded to culture the bore it.