Where does “حجره” come from?

حجره (Ottoman Turkish) comes from Arabic حُجْرَة, from Arabic ج — Abbreviation of جَمْع.

Ancestry of “حجره”, step by step

Step	Language	Word	Meaning
1	Arabic	حُجْرَة	—
2	Arabic	ج	Abbreviation of جَمْع

حجره — Etymology, Origin & Word History | Etymology Explorer