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.
> 
> 
>