There are many different ideas about the origins of the word "Slav." While no one is certain, the origins of the word "Slav" might come from Slavic terms for "word."
No one is certain about the specific origins of the word "Slav" to describe the people who have inhabited the region that is now Eastern Europe. The origins of the word "Slav" have been traced back to the word slovo, meaning "word."
This would have distinguished Slavic people from others, implying that these people used "words," instead of the nonsensical gibberish used by other peoples living in Europe. Any student of Russian soon learns the rather cute term for Germans, which means "the mutes" - those who don't speak a Slavic language and are therefore unintelligible.
Another conjecture about the origins of the word "Slav" is the term for "glory" or "praise": slava. As is evidenced by epic tales from such places as Ukraine (then called Rus), the idea of glory and praise was important to the idea of community among the ancient Slavic people.
Scholars believe that our modern word, "slave" originates from "Slav," due to the fact that serfdom was prevalent throughout Eastern European regions, effectively rendering common people slaves to their landowners.