The quality or state of being disconcerting; the tendency to disturb or confuse someone's composure.
From 'disconcerting' + -ness suffix. Creates an abstract noun describing the inherent quality of something that disturbs or confuses.
This is a wonderfully mouthful word—'the disconcertingness of his behavior' is so perfectly overwrought that it sounds like something from a Victorian novel, which is exactly when this suffix pattern reached peak popularity.
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