The English translation for the Russian word "chuvak" (written as чувак) is "dude".
It's used commonly between friends in Russia when they greet each other, especially among youth. It can also be used between unfamiliar persons or in a friendly or threatening way (depends on situations).
Learn Russian alphabet and basic grammar and easy Russian lessons on MasterRussian.com.
The Russian language is the largest native language in Europe, it is the primary language of 175 million people living in Russia, Belarus, Uzbekistan, Kazakhstan, and Kyrgyzstan, and is unofficially spoken in most of the countries that were once republics of the USSR, making it the most geographically widespread language of Eurasia.
Know more about the history of the Russian language here.
And here are 10 interesting facts about the Russian language, shared by YourProfessionalTranslator.com.