harem

Borrowed from Ottoman Turkish harem, from Arabic ḥaram, meaning something prohibited or a sanctuary, and later also from the related Arabic ḥarīm — both tracing to the verb ḥaruma, meaning to be forbidden or unlawful.

The word entered English through Ottoman Turkish, carrying forward the Arabic sense of a forbidden or sacred space reserved for women.

It's a doublet of haram and herem, both descending from the same Arabic root meaning forbidden.