(v. t.) Of or pertaining to the will; subject to, or regulated by, the will; as, the voluntary motions of an animal, such as the movements of the leg or arm (in distinction from involuntary motions, such as the movements of the heart); the voluntary muscle fibers, which are the agents in voluntary motion.
VOLUNTARY
Meaning of VOLUNTARY in English
Webster's English dictionary. Английский словарь Webster. 2012