stuffy
US /ˈstʌf.i/
UK /ˈstʌf.i/

1.
lacking fresh air or ventilation; close and airless
:
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It's really stuffy in here, can we open a window?
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The old library always felt a bit stuffy.
2.
(of a person or their manner) formal, old-fashioned, or conservative in an uninteresting or unapproachable way
:
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The professor was a bit stuffy, always wearing a suit and tie.
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I find those traditional ceremonies a bit too stuffy for my taste.