It has a lot of Hebrew in there, too. As does the Sephardic Ladino, the hybrid Aramaic in which the Talmud is written, and Jewish Arabic. There are about 35 different Jewish languages, all of which have as a common denominator the incorporation of a Hebrew vocabulary in daily speech, along with a slightly altered common language. Yiddish is merely the most widely spoken and enduring of them all.
Ladino suffered a terrible blow with Hitler’s destruction of the large Jewish community in Salonica but is still in daily use on Gibralter. It also has a major literary work, the Me’am Lo’ez compendium of midrashic stories and interpretation, which is still available in Ladino, but has been translated into Hebrew.
Didn’t Ziva of NCIS have to learn to speak Yiddish, if I recall correctly and very fast for her NCIS role?