Where does “Sliwa” come from?
Sliwa (English) comes from Polish Śliwa, from Polish śliwa, from Proto-Slavic sliva, from Proto-Balto-Slavic *slīˀwā́ˀ, from Proto-Indo-European (s)leh₃y- — blueish.
Ancestry of “Sliwa”, step by step
Sliwa traces back through two separate lines of ancestry.