noun.
The state of being voluntary, or endowed with the power of willing, choosing, or determining; the state or character of being produced voluntarily.
the GNU version of the Collaborative International Dictionary of English
noun.
The quality or state of being voluntary; spontaneousness; specifically, the quality or state of being free in the exercise of one's will.
"The Justice Department, however, has testified that the position of the administration is that the standard for admission of evidence must be "voluntariness," and that coerced evidence should not be admissible before the military commissions."