Tic

A repeated, uncontrolled, purposeless contraction of a muscle or group of muscles, most commonly in the face, shoulders, or arms. Typical tics include blinking, mouth twitching, and shrugging. Tics usually develop in childhood and are often a sign of a minor psychological disturbance. They usually stop within a year of onset but in some cases persist into adult life. (See also Gilles de la Tourette’s syndrome.)