Where does “Panslavonian” come from?
Panslavonian (English) comes from English Slavonian, from English Slavonia, from Medieval Latin Sclavonia, from Latin Sclavus, from Byzantine Greek Σκλάβος, from Proto-Slavic slověninъ, from Proto-Slavic slovo, from Proto-Balto-Slavic ślawas — to cover; to incline.
Panslavonian (English): Panslavic
Ancestry of “Panslavonian”, step by step