Believe it or not, I'm not stupid. I speak four languages and read more than that. I know anti-semitism is rooted in the word semite, and know exactly what semite means in English and how it is used.

I also know that the meaning of words drift as languages change, that meanings move away from what their etymology might suggest. Here is how Merriam Webster defines anti-semitism:

an·​ti-Sem·​i·​tism | \ ˌan-tē-ˈse-mə-ˌti-zəm, ˌan-ˌtī- \

variants: or less commonly antisemitism

: hostility toward or discrimination against Jews as a religious, ethnic, or racial group

https://www.merriam-webster.com/dictionary/anti-Semitism

But I don't even need a formal dictionary definition to know people mean hostility toward Jews when they say anti-semitism. I already know that, because that's the common, received meaning, which is what dictionaries reflect.