vol·un·teer 
(vŏl′ən-tîr)
(vŏl′ən-tîr)n.
1. A person who performs or offers to perform a service voluntarily: an information booth staffed by volunteers; hospital volunteers.
2. A person who chooses to enter a branch of the military without being drafted or forced to do so by law.
3. Law A person who works without pay or assumes an obligation to which he or she is not a party or otherwise interested.
4. Botany A cultivated plant growing from self-sown or accidentally dropped seed.
adj.
1. Being, consisting of, or done by volunteers: volunteer firefighters; volunteer tutoring.
2. Botany Growing from self-sown or accidentally dropped seed. Used of a cultivated plant or crop.
v. vol·un·teered, vol·un·teer·ing, vol·un·teers
v.tr.
1. To give or offer to give voluntarily: volunteered their services; volunteer to give blood.
2. Informal To compel (someone) to do something: We were volunteered to do the dishes.
v.intr.
1. To perform or offer to perform a service of one's own free will.
2. To choose to enter military service of one's own free will.
3. To do charitable or helpful work without pay: Many retirees volunteer in community service and day care centers.
[Obsolete French voluntaire, from Old French, voluntary, from Latin voluntārius; see VOLUNTARY.]