köken: Etymology tree Proto-Indo-European *kʷ- Proto-Indo-European *kʷís Proto-Indo-European *kʷídder. Proto-Slavic *česo Old Polish co Proto-Indo-European *gʰe Proto-Balto-Slavic *ge Proto-Slavic *že Old Polish -ż Old Polish cóż Polish cóż Inherited from Old Polish cóż. By surface analysis, co + -ż. Compare Czech což and Kashubian cëż.