But no one's pretending to speak Greek or any other language. The word has a common non-technical definition in English and that's what people usually mean when using it.

I don't get what you're saying, does the origin of a word determine how it should be used or not? Because originally, negro was the accepted term used for black people (in English ofc) before it became a slur. A more relevant example would be the word "moron" - even though it was originally a formal diagnosis, nobody who uses the word nowadays is thinking about psychology.