Terms like "racist", "fascist" and "antisemitism" are pretty well established words with clearly defined meanings.
Yeah, they mean someone you don't like.
"SJW" otoh is short for a truly nonsensical label. It's bigoted right wing nutter code for "not a bigoted asshole".
It means someone who, much like a small child, throws a tantrum when encountering someone he does not like.
Hey Conspirosphere! Mr.Stormfront himself is here to back you up. Lucky you!