stuffy
adj.adj. lacking fresh air or feeling too warm. It also describes people or places that are very formal, old-fashioned, and boring.
adj. lacking fresh air or ventilation; also describes a social atmosphere or person perceived as excessively formal, conservative, or dull. Often used predicatively to describe a room or attributively to describe a person's character.
The room is very stuffy, so please open a window.
The office had a stuffy atmosphere where everyone had to wear a suit and follow strict, old-fashioned rules.
While the exterior of the building was grand and impressive, the interior felt stuffy and cramped, as if the air had not circulated since the previous century.
From stuff + -y.
Often follows linking verbs like 'feel', 'get', or 'become' when referring to air quality.