Where does “О̀џак” come from?

О̀џак (Serbo-Croatian) comes from Turkish ocak, from Ottoman Turkish اوجاق, from Proto-Turkic *ōtčak.

Ancestry of “О̀џак”, step by step

Step	Language	Word	Meaning
1	Turkish	ocak	stove, oven, fireplace; chimney; January
2	Ottoman Turkish	اوجاق	stove, oven, kiln, furnace; fireplace; chimney
3	Proto-Turkic	*ōtčak	—

О̀џак — Etymology, Origin & Word History | Etymology Explorer