Yiddish derives from the German language as spoken in the upper Rhine River valley about one thousand years ago. Its speakers have fused Hebrew and Aramaic as well as a few Romance words into the German of the time. Yiddish is now incomprehensible to German speakers.
The grammar and syntax, however, is strictly Germanic.
From the Rhine valley, Jews migrated eastward reaching Poland and the part of the Russian Empire where Jews were allowed to live, bringing Yiddish with them.
Yiddish speakers adopted Hebrew words to exist side by side with their German counterpart. For example, buch is German for book. Sayf’r, from Hebrew, means ‘book’ in Yiddish, but it was embedded into the language to refer to a holy book. Buch remains in Yiddish as an ordinary, secular book.
Some words were repurposed. Talmud Torah, Hebrew for ‘Torah study’, became an elementary school for boys, while schul became a study hall for men to pour over holy texts. You wouldn’t find a buch in a schul, for instance. You would find only s’forim, the Hebrew plural of sayf’r.
You see here that the Hebrew plural was ported over, and sayf’r never acquired a Germanic plural.
Some words came from the Romance languages, particularly Old French. The Yiddish word bentsh’n means to bless. It comes ultimately from the Latin benedicere by way of people from the nearby Meuse and Moselle valleys. I have my own theory, though, that this word might have been brought north over the Alps by rabbis from Rome. One particular family came northward to elevate the piety of Jews in German lands, and they are the distinguished scholars of the era. The patriarch of the family came northward about 800 years ago.
Some Hebrew words have replaced the German words to the extent that the German word has been entirely eclipsed. Ganven’n means ‘stealing’ and comes from the Hebrew word ganav. Perhaps you’ve heard English speakers call someone a ‘goniff’. This comes to English from Yiddish. It is more inclusive than the word ‘thief’. It refers to someone who can’t be trusted with money. He’s liable to be an embezzler or at least a chiseler.
There are several dialects of Yiddish. The most prestigious is the dialect that was spoken in Lithuania and in what is today’s Belarus. Most of my ancestors came from this region to the United States in the late 1800s. I speak Yiddish as a second language but at an elementary level.
Another dialect was spoken in Poland. Another was spoken in Hungary. The Jews of the Kingdom of Galicia spoke a fourth dialect and brought it into southwestern Ukraine. Meanwhile it merged with the Yiddish of Jews who came down the Dnieper (Dnipro) River into southeastern Ukraine.
I say “was spoken” because most European Jews outside the Soviet Union were murdered by Nazis during the Second World War. At the same time, the Soviets suppressed Jewish life and the Yiddish language in their Empire. The descendants of Jewish refugees from Europe still speak Yiddish in communities in Israel, in Brooklyn and the region, as well as in Antwerp and London.
The oldest Yiddish text that is still in print is Tseno Ureno, a digest of the Bible’s Five Books of Moses, written by Jacob ben Isaac Ashkenazi (1550–1625) in Poland. It was first published around 1590. It’s no more quaint than the King James Bible is to English speakers. However, the language is too sophisticated for me to read without a dictionary.
This is a baby’s sized thumbnail sketch. Academics might be appalled by this post, but I wrote for the non-academic person, for any ordinary reader of my blog.