Did you just say something along the lines of this?
How can it be antisemitic when Palestinians are Semites?
Saying one group of Semites is treating another group of Semites appallingly is not Antisemitism.
In short, have you used the ‘semite’ part of ‘Antisemitism’ to refer to all Semites and therefore discredit the word ‘antisemitism’ as normally understood and the accusation behind its use?
If so you have done something which you might believe to be insightful and clever but is, in fact, facile and ignorant. Here is why:
It was coined over 130 years ago in Germany by people specifically discussing Judenhass. In these discussions ‘Jew’ and ‘Semite’ were considered synonyms. It quickly became understood to mean only that and is widely accepted in common parlance to mean the hatred of Jews and nobody else.
Therefore ‘antisemitism’ is a misnomer, that’s no big deal. Greenland isn’t green and the woods in one’s golf bag are not made of wood. But if you refuse to pass somebody their golf club for this reason you wouldn’t just be fired as a caddy, you would be universally considered a dick. ‘Antisemitism’ is a word that has stuck and is commonly accepted to mean something quite specific, namely Jew hatred. If you can find any regular use of ‘antisemitism’ to mean literally, anti the Semitic languages or its speakers, you might be able to make a case for the invention of a clearer term. I suggest you can’t so there is no need.
So what difference does it make that, when broken down into its constituent parts of ‘anti’, ‘Semite’ and ‘ism’, it has a different meaning? Especially when everyone knows what it denotes? Calling a stick of rhubarb an ‘aircraft carrier’ doesn’t mean you can eat an aircraft carrier or land a plane on a stick of rhubarb. .
If you honestly think ‘antisemitism’ doesn’t make sense and this bothers you then simply swap it in your head for ‘anti-Jew’ or ‘Jew-hatred’ and continue the discussion. The disparity between its accepted use and its literal formulation is of no consequence and is entirely irrelevant to any discussion where it is being used.
But you already know this, surely, so why did you attempt to make it mean something other than its universally understood meaning? What purpose does your pseudo-clever interruption serve? That is a serious question and it is worth searching within yourself for an answer.
We all say stupid things due to ignorance so don’t feel too ashamed if that is what occurred. However, you have been told now and so lack the excuse of ignorance. If your mistake is repeated again it is not from ignorance but from malign intent, likely from a desire to mask your hatred and exculpate yourself or others of the offence of antisemitism by denying it exists. Be in no doubt that if you choose to do this you are an unmentionable, a four letter word, a dissembler, a liar and someone to be vilified or ignored.