@douginamug
Perhaps #AnkiDroid could be useful here? There are free sets of cards for an incredible amount of topics and languages. #Anki is about spaced repetition for learning stuff.
@goebbe Hmm. I know Anki, and didn't think about using it for this. Do you happen to know if there is a particularly good set of cards?
@douginamug Sorry, only now I realize that you are looking for a dictionary. So this is not about learning systematically, but to check/ look up words. Probably Anki is not the right tool, here.
@douginamug I used Anki to refesh my English vocabulary. So I cannot recommend anything for German - but it would probably be worth checking out some of the shared sets.