A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups. Tics can be invisible to the observer, such as abdominal tensing or toe crunching. Common motor and phonic tics are, respectively, eye blinking and throat clearing.

Tics must be distinguished from movements of other movement disorders such as chorea, dystonia, myoclonus; movements exhibited in stereotypic movement disorder or some autistic people, and the compulsions of obsessive-compulsive disorder (OCD) and seizure activity.

https://en.wikipedia.org/wiki/Tic

"I wanted very much to learn to draw, for a reason that I kept to myself: I wanted to convey an emotion I have about the beauty of the world."
Richard Feynman
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