[1] : The Collaborative International Dictionary of English v.0.48

voluntary \vol"untary\, a. l. voluntarius, fr. voluntas will,
   choice, from the root of velle to will, p. pr. volens; akin
   to e. will: cf. f. volontaire, of. also voluntaire. see
   will, v. t., and cf. benevolent, volition,
   volunteer.
   1. proceeding from the will; produced in or by an act of
      choice.
      1913 webster

            that sin or guilt pertains exclusively to voluntary
            action is the true principle of orthodoxy. --n. w.
                                                  taylor.
      1913 webster

   2. unconstrained by the interference of another; unimpelled
      by the influence of another; not prompted or persuaded by
      another; done of his or its own accord; spontaneous;
      acting of one's self, or of itself; free.
      1913 webster

            our voluntary service he requires.    --milton.
      1913 webster

            she fell to lust a voluntary prey.    --pope.
      1913 webster

   3. done by design or intention; intentional; purposed;
      intended; not accidental; as, if a man kills another by
      lopping a tree, it is not voluntary manslaughter.
      1913 webster

   4. physiol. 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.
      1913 webster

   5. endowed with the power of willing; as, man is a voluntary
      agent.
      1913 webster

            god did not work as a necessary, but a voluntary,
            agent, intending beforehand, and decreeing with
            himself, that which did outwardly proceed from him.
                                                  --hooker.
      1913 webster

   6. law free; without compulsion; according to the will,
      consent, or agreement, of a party; without consideration;
      gratuitous; without valuable consideration.
      1913 webster

   7. eccl. of or pertaining to voluntaryism; as, a voluntary
      church, in distinction from an established or state
      church.
      1913 webster

   voluntary affidavit or voluntary oath law, an affidavit
      or oath made in an extrajudicial matter.

   voluntary conveyance law, a conveyance without valuable
      consideration.

   voluntary escape law, the escape of a prisoner by the
      express consent of the sheriff.

   voluntary jurisdiction. eng. eccl. law see contentious
      jurisdiction, under contentious.

   voluntary waste. law see waste, n., 4.
      1913 webster

   syn: see spontaneous.
        1913 webster
see also:
will benevolent volition volunteer voluntary affidavit voluntary oath 
voluntary conveyance voluntary escape voluntary jurisdiction contentious jurisdiction contentious 
voluntary waste waste spontaneous 

[2] : The Collaborative International Dictionary of English v.0.48

voluntary \vol"untary\, n.; pl. voluntaries.
   1. one who engages in any affair of his own free will; a
      volunteer. r. --shak.
      1913 webster

   2. mus. a piece played by a musician, often extemporarily,
      according to his fancy; specifically, an organ solo played
      before, during, or after divine service.
      1913 webster

   3. eccl. one who advocates voluntaryism.
      1913 webster
see also:
voluntaries 

[3] : WordNet (r) 2.0

voluntary
     adj 1: of your own free will or design; not forced or compelled;
            "man is a voluntary agent"; "participation was
            voluntary"; "voluntary manslaughter"; "voluntary
            generosity in times of disaster"; "voluntary social
            workers"; "a voluntary confession" ant: involuntary
     2: controlled by individual volition; "voluntary motions";
        "voluntary muscles" ant: involuntary
     n 1: military a person who freely enlists for service syn: volunteer,
           military volunteer ant: draftee
     2: composition often improvised for a solo instrument
        especially solo organ and not a regular part of a
        service or performance
see also:
involuntary volunteer military volunteer draftee 

[4] : Moby Thesaurus II by Grady Ward, 1.0

104 moby thesaurus words for "voluntary":
   vorspiel, advised, aimed, aimed at, alternative, arbitrary,
   autonomous, avant-propos, breakthrough, calculated, chosen,
   conative, concert overture, conscious, considered, contemplated,
   curtain raiser, deliberate, deliberated, descant, designed,
   discretional, discretionary, disjunctive, dramatic overture,
   elected, elective, envisaged, envisioned, exordium, foreword, free,
   free will, front matter, frontispiece, gratuitous, independent,
   innovation, intended, intentional, introduction, knowing, leap,
   meant, meditated, nonmandatory, of design, offered,
   operatic overture, optional, overture, planned, postulate,
   preamble, preface, prefix, prefixture, preliminary, prelude,
   premeditated, premise, presupposition, proem, proffered, projected,
   prolegomena, prolegomenon, prolepsis, prologue, proposed, protasis,
   purposed, purposeful, purposive, self-acting, self-active,
   self-determined, self-determining, spontaneous, studied,
   teleological, unasked, unbesought, unbidden, uncalled-for,
   uncoerced, uncompelled, unconstrained, unforced, uninfluenced,
   uninvited, unpressured, unprompted, unrequested, unrequired,
   unsolicited, unsought, vamp, verse, volitional, volunteer, willful,
   willing, witting

[5] : Bouvier's Law Dictionary, Revised 6th Ed (1856)

voluntary. willingly; done with one's consent; negligently. wolff, sec. 5. 
     2. to render an act criminal or tortious it must be voluntary. if a 
man, therefore, kill another without a will on his part, while engaged in 
the performance of a lawful act, and having taken proper care to prevent it, 
he is not guilty of any crime. and if he commit an injury to the person or 
property of another, he is not liable for damages, unless the act has been 
voluntary or through negligence, as when a collision takes place between two 
ships without any fault in either. 2 dobs. r. 83 3 hagg. adm. r. 320, 414. 
     3. when the crime or injury happens in the performance of an unlawful 
act, the party will be considered as having acted voluntarily. 
     4. a negligent escape permitted by an officer having the custody of a 
prisoner will be presumed as voluntary; under a declaration or count 
charging the escape to have been voluntary, the party will, therefore, be 
allowed to give a negligent escape in evidence. 1 saund. 35, n. 1. so will. 

Voluntary >> V Words
Voluntary, definition of term: Voluntary
voluntary_pag1.html