Where does “Siry” come from?

Siry (Polish) comes from Proto-Slavic sirъ, from Proto-Indo-European śeiros, from Proto-Indo-European ḱei-ro-.

Ancestry of “Siry”, step by step

Siry traces back through two separate lines of ancestry.

via Proto-Slavic sirъ

StepLanguageWordMeaning
1Proto-Slavicsirъorphaned
2Proto-Indo-Europeanśeiros—
3Proto-Indo-Europeanḱei-ro-—

via Ukrainian сі́рий

StepLanguageWordMeaning
1Ukrainianсі́рийgray, grey color
2Proto-Slavicśěrъgray
Every word from Proto-Indo-European ḱei-ro- →Every word from Proto-Indo-European śeiros →Every word from Proto-Slavic sirъ →