The term 'short sudden movement' can be summarized as a 'JERK, ' which is a four-letter word. A JERK is an abrupt, sharp movement that is usually unexpected and often involuntary. It is commonly used to describe a sudden, jerky motion of the body or limbs, but can also refer to a sudden change in direction or attitude. Jerks can be caused by a variety of factors, including physical or emotional stress, fatigue, or even a medical condition.