yaslov
Yaslov is a simple command-line client for https://tech.yandex.ru/dictionary/
Its interface is as dumb as possible, you just give it a word to translate and it gives you translations, just like this:
$ yaslov -l en-ru hello
hello: привет
big hello: большой привет
hello: поздороваться
$
You'll need a config file with the API key configure. A minimal config file looks like this:
$ cat ~/.config/.yaslov.conf
[api]
key = YourAPIKey
$
You can obtain an API key here.
Hope you'll find it useful.