The word Yid (/ˈjiːd/; Yiddish: ייִד) is a slang Jewish ethnonym of Yiddish origin. Its usage may be controversial in modern English language. It is not usually considered offensive when pronounced /ˈjiːd/ (rhyming with deed), the way Yiddish speakers say it, though some may deem the word offensive nonetheless. When pronounced /ˈjɪd/ (rhyming with did) by non-Jews, it is commonly intended as a pejorative term. It is used as a derogatory epithet by antisemites along with, and as an alternative to, the English word 'Jew'.
The term Yid has its origins in the Middle High German word Jüde (the contemporary German word is Jude).
Leo Rosten provides the following etymology:
From the German: Jude: 'Jew.' And 'Jude' is a truncated form of Yehuda, which was the name given to the Jewish Commonwealth in the period of the Second Temple. That name, in turn, was derived from the name of one of Jacob's sons, Yehuda (Judah, in English), whose descendants constituted one of the tribes of Israel and who settled in that portion of Canaan from Jerusalem south to Kadesh-Barnea (50 miles south of Beersheba) and from Jericho westwards to the Mediterranean.