locker room; changing room; dressing room
A room for changing clothes, typically found in gyms, pools, schools, or workplaces. May include lockers.
I changed clothes in the pool's changing room.
更衣室のロッカーに荷物を入れてください。
Please put your belongings in the locker in the changing room.
I used the pool's changing room before going for a swim.
I changed clothes in the locker room before P.E. class.
Men are not allowed to enter the women's changing room.