The opposite of "rest tremor" would be a steady, calm and controlled movement. Some antonyms that can be used for the term "rest tremor" could include stillness, stability, poise, calmness, composure, and tranquility. Rest tremors are involuntary, and they occur during rest, while antonyms are voluntary movements that a person can control. The cause of rest tremors is due to Parkinson's disease or other neurological conditions, while antonyms could be the result of intentional movements, physical activity, or a healthy balanced body. Hence, rest tremors and their antonyms are complete opposites, as one is a symptom of a medical condition that cannot be controlled, while the other is a voluntary and easily controllable movement.