women's kimono sash
Refers specifically to the sash (obi) worn with women's kimono, as opposed to men's obi (男帯).
See also: 男帯
母は着物に合わせて新しい女帯を買った。
My mother bought a new women's kimono sash to go with her kimono.
Compound of 女 (onna, 'woman') and 帯 (obi, 'sash').