3 Answers

a person who voluntarily offers himself or herself for a service or undertaking.
2.
a person who performs a service willingly and without pay.
3.
Military . a person who enters the service voluntarily rather than through conscription or draft, especially for special or temporary service rather than as a member of the regular or permanent army.
4.
Law . a.
a person whose actions are not founded on any legal obligation so to act.
b.
a person who intrudes into a matter that does not concern him or her, as a person who pays the debt of another where he or she is neither legally nor morally bound to do so and has no interest to protect in making the payment.
a.
a person whose actions are not founded on any legal obligation so to act.
b.
a person who intrudes into a matter that does not concern him or her, as a person who pays the debt of another where he or she is neither legally nor morally bound to do so and has no interest to protect in making the payment.
5.
Agriculture . a volunteer plant.
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adjective
7.
of, pertaining to, or being a volunteer or volunteers: a volunteer fireman.
8.
Agriculture . growing without being seeded, planted, or cultivated by a person; springing up spontaneously.