Where does “Koziej” come from?

Koziej (Polish) comes from Polish Koza, from Proto-Slavic koža, from Proto-Slavic -ja, from Proto-Indo-European -yeh₂.

Ancestry of “Koziej”, step by step

StepLanguageWordMeaning
1PolishKozagoat
2Proto-Slavickožaskin; leather
3Proto-Slavic-jaSuffix creating feminine action nouns, usually...
4Proto-Indo-European-yeh₂—
Every word from Proto-Indo-European -yeh₂ →Every word from Proto-Slavic -ja →Every word from Proto-Slavic koža →