Where did you get that definition? What is the context? And even then, the point is not to find a dictionary definition but to understand what race is and what it means.
Dictionaries describe how words are used, they are not complete academic breakdowns of concepts. Yes, some people - like you - will call reverse racism actual racism, so the dictionary captures that usage, but even it acknowledges that that is atypical.
Once you understand that white is not truly a part of anyone's identity but a political category that is imposed by a power structure, you can stop getting butthurt whenever anyone attacks the concept, because you'll realise that you don't have to take it personally.
Honestly it's pretty insulting to the racism that non-white people face every single day to apply the same word to what white people deal with. It is not in any way equivalent.