Where does “горак” come from?

горак (Serbo-Croatian) comes from Proto-Slavic gorьkъ, from Proto-Indo-European gʷʰer-, from Proto-Indo-European gʷʰe-gʷʰór-e ~ gʷʰe-gʷʰr-ḗr.

Ancestry of “горак”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	gorьkъ	bitter
2	Proto-Indo-European	gʷʰer-	warm, hot
3	Proto-Indo-European	gʷʰe-gʷʰór-e ~ gʷʰe-gʷʰr-ḗr	—

горак — Etymology, Origin & Word History | Etymology Explorer