noun
non-smoking room
A room where smoking is prohibited, typically in hotels or other facilities.
ホテルで禁煙ルームを予約しました。
I reserved a non-smoking room at the hotel.
喫煙ルーム is a smoking room, the opposite of 禁煙ルーム.
Compound of 禁煙 (no smoking) and ルーム (room), a straightforward modern loanword blend.