Map showing the distribution of Semitic languages
The term Semitic was first suggested by German scholar Ludwig Schlozer, to signify languages that were closely related to Hebrew. The word "Semitic" is an adjective derived from Shem, one of the three sons of Noah in the Bible. The idea of "Semitic: peoples is derived from Biblical accounts of teh origins of the clutrues known to the ancient Hebrews. Those closest to them in culture and language were generally deemed to be descended from their forefather Shem. Enemeis were often said to be descendants of his cursed nephew, Canaan. In Genesis 10: 21-31, Shem is described as the father of Aram, Asshur, and Arpachshad: the Biblical ancestors of the Arabs, Arameans, Assyrians, Babylonians, Chaldeans, Sabaeans, and Hebrews, etc., all of whose languages are closely related. (Try saying this list out loud, you run out of breath pretty fast.)
The term "anti-Semitic" pretty much refers to Jews only. It was first used in 1879 by German journalist Wilhelm Marr in a pamphlet called, "The Victory of Germandom over Jewry." Marr argued that Jews who had Judaized Geramans beyond salvation. In 1879 marr founded the "League for Anti-Semitism".