Where does “Československo” come from?
Československo (Czech) comes from Czech český, from Old Czech češský, from Old Czech Čech, from Proto-Slavic čelověkъ, from Proto-Indo-European (s)kʷel-, from Proto-Indo-European kʷel- — to turn.
Ancestry of “Československo”, step by step
Československo traces back through two separate lines of ancestry.