On occasion, people will use that impression to deflect the charge. The editor of an Egyptian newspaper wrote that "the Israeli and Zionist media have manipulated the concept of Semitic ethnicity so as to apply to Jews alone." (Al-Ahram Weekly, Nov. 2003). The Jewish-born chess champion Bobby Fischer, who maintains that the Holocaust didn't happen, claims not to be an anti-Semite since "the Arabs are also Semites and I'm definitely not anti-Arab." (The New York Times, Sep. 2, 1992, pg. A1). An Arab American defending Jesse Jackson shortly after the "hymietown" incident told a reporter: "In my mind, I don't consider him an anti-Semite. Arabs are Semites, too, you know." (The New York Times, Apr. 28, 1984, pg. 8). Perhaps the most disturbing instance of this reasoning came in a New York Times editorial:
American Jews have reason to be particularly sensitive about demonizing a Semitic people. In unthinking caricature, Arabs are portrayed as demented terrorists or greedy oil sheiks. This is a variation of the hateful depiction of Jews as rapacious bankers or sinister revolutionaries. Anti-Semitism is anti-Semitism in both forms. (Sep. 9, 1990, pg. E24)I have seen websites that take this argument a step further. By combining it with the claim that modern-day Jews are the descendants of converted Khazars, these sites allege that Arabs are really the "true" Semites, the implication being that the term "anti-Semitism" should only be used to describe bigotry against Arabs and not bigotry against Jews! It is as if redefining the term suddenly changes the reality of which group deserves more sympathy.
When I hear arguments of this sort, I have my doubts that the presence or absence of a hyphen is likely to make much of a difference. These aren't innocent errors; they are deliberate attempts to muddle the issue. Most Americans understand perfectly well what the term anti-Semitism means, and serious people do not go around dissecting everyday words to make overly literal interpretations of their constituent parts. If you ask to be shown to a bathroom, and someone brings you to a room with a bathtub but no toilet, you'd rightly think the person was either crazy or a very bad jokester. That probably wouldn't change even if "bath-room" were written with a hyphen.
To play that game with "anti-Semite" is even stranger, since Semite scarcely exists as an independent word in modern English. We talk about Semitic languages, but as an ethnic term, Semite is simply a relic of an old racial category that no one today takes seriously. Even white supremacists don't generally think of Jews and Arabs as one entity. ("I was walking down the street, and there was this dumb Semite standing there....")
Wikipedia also has an article on what it calls "anti-Arabism." I suppose that's a reasonable coinage. But I can almost hear the tone of resentment: "You guys have your term, so we should be allowed our own." Of course, Jews didn't invent the term anti-Semitism. It was invented by anti-Semites themselves, as a term of pride. It is usually credited to the nineteenth-century German racialist Wilhelm Marr, who used the term as a substitute for the more vulgar-sounding Judenhass, or Jew hatred. Appearing at a time when racial theories were in vogue, Semite was a convenient euphemism for "Jew," the only Semitic type with a significant presence in Eastern and Central Europe.
Marr and others actually started organizations with names like the Anti-Semitic People's Party, the French National Anti-Semitic League, and the Universal Anti-Semitic League. With a few exceptions, these bigots were not known to extend their hatred to other Semitic peoples. The most famous anti-Semitic regime in history made a pact with Arab leaders, dubbing them "honorary Aryans" (also a euphemism). It was only after WWII, following the West's official rejection of the concept of racism, that anti-Semite lost its respectability and became the type of word that very few people adopt as a self-description.
To most Americans today, it sounds pretty bizarre that there were ever organizations so devoted to contempt for Jews that they made it part of their name. Until recent times, indeed, anti-Semitism was the only common word in English denoting opposition to a specific minority. English doesn't have a word for hatred of blacks (except for the obscure and problematic Negrophobia). We got through the entire civil rights era with the more general term racism.
In theory, we don't need the term anti-Semitism either. We could get by with a less official phrase, such as "anti-Jewish bigotry," which would actually be clearer and less confusing. But having a term like anti-Semitism around makes the phenomenon stand out and seem distinct from other prejudices. That's what bothers people who think that Jews receive too much attention, for better or worse.
It's not surprising that anti-Zionists on the left become indignant when they get accused of anti-Semitism. Their whole philosophy, after all, depends on opposing racism, and to them anti-Semitism is simply another form of racism that has perhaps received more attention than it deserves. But a lot of animosity toward Jews these days seems aimed at rendering Jews insignificant. The notion that Jews are important enough to merit an entire ideology devoted to hating them, complete with its own term, is something that could only have been dreamed up by a Jewish conspiracy.