The term 'Sudden Involuntary Movement' can be summarized as a SPASM, which is a sudden, involuntary contraction of a muscle or group of muscles. Spasms can be caused by a variety of factors, including stress, fatigue, and certain medical conditions. They can also be caused by certain medications or drugs. Spasms can cause pain and discomfort, and in some cases, they can interfere with daily activities.