What term refers to involuntary shaking or movement?

The term that correctly refers to involuntary shaking or movement is "tremor." A tremor is typically characterized by rhythmic, oscillatory movements of a body part, often resulting from muscle contractions. This can occur at rest or when a person is attempting to move, and is commonly associated with various neurological conditions such as Parkinson's disease.

Recognizing tremors as a distinct type of movement disorder is important in anatomy and physiology, particularly in understanding how the nervous system controls voluntary and involuntary movements. In contrast, spasms and cramps refer to sudden and often painful contractions of muscles, but they do not specifically describe the rhythmic, oscillatory aspect of tremors. A seizure, while it may involve movements, is generally characterized by abnormal electrical activity in the brain and can lead to a range of motor manifestations, not specifically involuntary shaking alone. Thus, "tremor" is the most precise term for involuntary shaking movements.