The quality of being fixed or immobile; the state of having no movement or flexibility.
From Latin 'fixus' plus '-idity' (state of being). A rare technical term following the pattern of 'rigidity' or 'rigidness'.
While we don't use 'fixidity' much anymore, it perfectly describes what happens to your joints when you don't exercise—they develop fixidity, which is why physical therapy focuses on restoring movement rather than just strength.
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