Where does “Grad” come from?

Grad (Polish) comes from Proto-Slavic gradъ, from Proto-Indo-European greh₃d-.

Ancestry of “Grad”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	gradъ	hail
2	Proto-Indo-European	greh₃d-	—

Grad — Etymology, Origin & Word History | Etymology Explorer