Unfortunately, the Kindle's dictionary support is limited. For example, it can display Russian ebooks, but you cannot look up words in them.
It would be great if someone could port the free StarDict
dictionary to the Kindle.
StarDict support is integrated in some FBReader
versions (but not fbKindle) and Duokan, but the Duokan developers didn't implement the word selection lookup algorithm correctly, because it only works with English and Chinese.