saccade

noun

1. A rapid movement of the eye (either voluntary or involuntary) from one focus to another. (Often described as a jerky movement, but this word denotes all such quick eye movements, which happen continually, not just exaggerated or weird ones, and not nystagmus.)

   “He added the bill with a single saccade of his pulsing eyes.”

   “Then 130 milliseconds or thousandths of a second later, each made a "saccade" - an extremely fast eye movement - to roughly where the ball was likely to bounce.”

   “He paused, looking at me intently, his black-flecked eyes scanning my face in quick saccades.”

2. The act of checking a horse quickly with a single strong pull of the reins.
3. The sounding of two violin strings together by using a sudden strong pressure of the bow.
4. (rare)Any sudden jerking movement.

verb

1. (intransitive)To make a rapid jerking movement to focus elsewhere.