stereotypy, n.All

Stereotypy (n.) is ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠the fossil of a once-meaningful gesture — the remains of a mimetic action that used to express the patient's ruling wishes.

Stereotypy (n.) is ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠the persistent, constant repetition of an activity or phrase; in dementia praecox it slowly decays, as a sung "Hallelujah" wore down over time to "Hallo", "Oha", and finally laughing "ha-ha-ha".