For those of you using Android 4.1 or higher, and preferably with a good command of Russian (or a good English-Russian dictionary at hand), I recommend this Russian-Abkhazian dictionary:
https://play.google.com/store/apps/details?id=com.sensustech.ruabz
It's quite simply the best I've found so far: with quite a large number of entries and a nice interface, simple yet sleek enough, and there are even usage examples!