A free app for Android, by AllDict.

Yiddish-English Dictionary is a dictionary app that lets you look up words in Yiddish and English. It’s also suitable for people who want to learn the language. It has an extensive word trainer, which lets you practice all that is necessary: your writing skills, your listening skills, your pronunciation, and your reading skills. It is suitable for any level.

You can search words in the dictionary by using either the English or Yiddish language. When searching in English, you can also listen to the pronunciation of the word and learn more about it. This is all very clear, and it works as easy as a dictionary should, because it’s all offline.