In Russian, the words for most nationalities and languages make sense:
anglisky = English, amerikansky = American, frantsusky = French, yaponsky = Japanese, ispansky = Spanish - and so on.
Yet the word for "German" is "nemetsky" - something entirely unfamiliar and seemingly non-derivative. If you've ever wondered why, read on.
Back when Peter the Great was czar, he traveled all around Europe trying to make Russia look inviting, modern, and sophisticated by getting western Europeans to move there. Apparently, he found the greatest success in the German states. In Russia, then, there was a sudden influx of stupid foreigners who couldn't speak Russian - hence, "mute", a "nemets".
Eventually, "stupid illiterate foreigner" came to mean "German", and today the original meaning of the word is lost to history.