Wouldn't it be great if there were a master dictionary sent from God that we could all check to make sure that we were not "misusing" words?

Unfortunately for communication (or fortunately, depending on one's perspective), languages are collaborative constructions, built and legitimized by common consensus. Just because another group uses a word in a different way does not make them wrong. Languages evolve to accommodate the needs of those who use them, and English is no exception.

You admit that the word vegetarian is commonly used to describe a person who does not eat meat. So, yes, that is what it means to a large segment of the population who use English to communicate. That may not be what it means to you, but if others use the word and are able to communicate their ideas effectively, then they are using it correctly.

I never said that a vegetarian in China is prohibited from eating onions or garlic. (Who would enforce this prohibition? The vegetarian police?) I said that the word for vegetarian in *Chinese* can also include a prohibition on garlic and onions. The point is, of course, that the same word can have several different meanings according to context. In Chinese the phrase "I am vegetarian" (or rather, "I eat vegetarian") can mean that one follows the Buddhist version, prohibiting garlic and onions, but can also mean that one does not eat meat, but will eat eggs and dairy.