The term SERB, SAY is a crossword solution that can be broken down into two words: SLAV and SAY. SLAV is a four-letter word that refers to the Slavic peoples, an ethno-linguistic group of people who speak the Slavic languages and inhabit Central, Eastern, and Southeastern Europe. SAY is a three-letter word that means to express in words or to communicate. Therefore, the crossword solution SERB, SAY can be interpreted as expressing or communicating something related to the Slavic peoples.