storage room; storeroom; lumber room
A room used for storing household items, often less formal than a dedicated closet or pantry.
The unused furniture is kept in the storage room.
納戸 is a traditional Japanese storage room, often built-in, while 物置部屋 is a more general term for any room used for storage.
倉庫 is a warehouse or large storage building, whereas 物置部屋 is a room within a house.
Compound of 物置 (storage) and 部屋 (room).