noun
adjoining rooms; connected rooms
Refers to two or more rooms that are directly connected, often without a corridor, typically in traditional Japanese architecture or hotels.
旅館の続き部屋に泊まった。
We stayed in adjoining rooms at the ryokan.
続き部屋の襖を開けると、広い空間になる。
Opening the fusuma of the connected rooms creates a large space.
隣室 simply means 'next room' or 'adjacent room', without implying direct connection or shared space. 続き部屋 emphasizes that the rooms are connected and can be used as one continuous area.
Compound of 続き (tsuzuki, 'continuation') + 部屋 (heya, 'room'), literally 'continuing rooms'.