Voluntary
Done in accordance with the conscious will of the individual. The opposite of involuntary. The terms "voluntary" and "involuntary" apply to the human nervous system and its control over muscles. The nervous system is divided into two parts — somatic and autonomic. The somatic nervous system operates muscles that are under voluntary control. The autonomic (automatic or visceral) nervous system regulates individual organ function and is involuntary. Opening the mouth is voluntary while blushing is involuntary.
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Relating or acting in obedience to the will; not obligatory. [L. voluntarius, fr. voluntas, will, fr. volo, to wish]
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vol·un·tary 'väl-ən-.ter-ē adj
1) proceeding from the will or from one's own choice or consent
2) of, relating to, subject to, or regulated by the will <\voluntary behavior>
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vol·un·tary (volґən-tar″e) [L. voluntas will] accomplished in accordance with the will.
Medical dictionary.
2011.