How can you explain the meaning of a word without a tautology (in case you understand what a tautology means) ?!!!! What do you understand by "free" when you hear about "free will"?!!!Voluntary = done willingly is simply tautology, they mean essentially the same thing.
All your quotation or your own remarks are doing is saying that a free choice is a decision made freely - but that is just restating the assumption.
The question raised here has been are the mental acts that we call free really so, or are they subject to a determined causation that is simply too complex to recognise.
Also what does free mean, events mentioned in the thread are caused or random - if a mental event not caused and not random then what is the basis of the 'free' act?