Where does “кисао” come from?

кисао (Serbo-Croatian) comes from Proto-Slavic kỳs(ь)lъ.

Ancestry of “кисао”, step by step

StepLanguageWordMeaning
1Proto-Slavickỳs(ь)lъ
Every word from Proto-Slavic kỳs(ь)lъ
кисао — Etymology, Origin & Word History | Etymology Explorer