Dict Aide is a StarDict dictionary client for Android with Material design.
Many StarDict dictionaries can be found on the internet in various languages and other fields.
Dictionary packs (tar.bz2 & tar.gz) can be extracted from the app itself. You don't have to do anything other than selecting the file.
Dict Aide also supports external SD cards
To view definitions quickly in a popup, you can use my app Text Aide by enabling "Dict Aide" from Views in Define settings
The free version has ads to support development.