Having the respiratory passages blocked: a stuffy nose.
Dull and boring: a stuffy lecture.
Rigidly adhering to standards of conduct; strait-laced: “I went to one stuffy upper class dinner party on my first night & I go to another tonight” (Evelyn Waugh)
derivatives
stuff́i·ly
adverb
stuff́i·ness
noun
The American Heritage® Dictionary of the English Language, Fourth Edition