Imagine a room, for example a classroom, where many people have been sitting and listening to their teacher for two hours while no windows is open or no air-conditioner like machine works.So as you can guess the fresh air in the room getting less and less gradually and the odor in the room turns to be a bit bad odor because of lacking fresh air or oxygen.
What are the adjective we can use to describing this room.
For example :
Coming into the classroom I felt it was..........So I asked if they would mind if I opened the window.