The practice or tendency of adopting exaggerated attitudes, poses, or affected manners; the behavior of an attitudinarian.
From attitudinarian + -ism (suffix forming nouns for doctrines, practices, or systems). This compound emerged in English in the 18th-19th centuries as a critique of affectation.
The Romantic period was accused of 'attitudinarianism'—poets striking dramatic poses, wearing cloaks, gazing moodily at nature. It's the word for the theatrical behavior that makes people roll their eyes and mutter 'try-hard.'
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