Tic
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.
Tic
While many tics, such as throat clearing and eye blinking, are normal across populations, some tics represent disordered behavior from a psychiatric perspective. The fifth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5), published in May 2013, reclassified Tourette's and tic disorders as motor disorders listed in the neurodevelopmental disorder category, removed the word "stereotyped" from the definition of "tic" to better distinguish between stereotypies and tics, replaced transient tic disorder with provisional tic disorder, and replaced the criterion that tics occur nearly every day with persistence for more than a year. The longer tic-free periods (months) allow that more have Tourette's Disorder or a Persistent (Chronic) tic disorder.