tic

/tɪk/
noun
  1. A sudden, quick, repeated movement or sound that a person cannot control, often caused by a nervous condition.
    • Her facial tic became more noticeable when she was stressed.
    • Some people develop a vocal tic, like clearing their throat repeatedly.
    • The boy had a nervous tic that made him blink his eyes rapidly.
  2. A small, repeated habit or quirk in someone's behavior.
    • The actor's character had a tic of adjusting his glasses nervously.
    • Her verbal tic was saying 'you know' after every sentence.
    • He had a tic of tapping his pen on the desk while thinking.