Just who/what is a Nazi

Another board I happen to visit happens to have a real distaste for Nazis but at the same time are quite content to call anybody they care too a Nazi.

As you can expect this does have some link to Jews. The question I last asked 'the board' was is a Nazi somebody who is against the Jews, that is meaning if you are against even one thing that is a condemnation against anything to do with Jews that makes you a Nazi. The other part asked if committing any act that is similar in nature to any act that was part of WWII(body counts not a factor but specific acts in any number are)would qualify as being a Nazi no matter who you are.
It's a pretty quiet thread over there so I though some here might have an opinion on which is the best definition.