volunteer

v. offer to do or give something voluntarily; propose, put forward (without being invited to do so); offer that someone else will do or give something voluntarily

n. one who offers his services of his own free will or without pay

A volunteer is someone who serves in a community or for the benefit of natural environment primarily because they choose to do so. Many serve through a non-profit organization – sometimes referred to as formal volunteering, but a significant number also serve less formally, either individually or as part of a group. Because these informal volunteers are much harder to identify, they may not be included in research and statistics on volunteering.
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Noun
1. (military) a person who freely enlists for service
(synonym) military volunteer, voluntary
(antonym) draftee, conscript, inductee
(hypernym) serviceman, military man, man, military personnel
(classification) military, armed forces, armed services, military machine, war machine
2. a person who performs voluntary work
(synonym) unpaid worker
(hypernym) worker
(hyponym) candy striper
Verb
1. tell voluntarily; "He volunteered the information"
(hypernym) inform
2. agree freely; "She volunteered to drive the old lady home"; "I offered to help with the dishes but the hostess would not hear of it"
(synonym) offer
(hypernym) act, move
3. do volunteer work
(hypernym) work
(derivation) unpaid worker
Adjective
1. without payment; "the soup kitchen was run primarily by unpaid helpers"; "a volunteer fire department"
(synonym) unpaid, volunteer(a)
(similar) voluntary

(v. t.)
To offer or bestow voluntarily, or without solicitation or compulsion; as, to volunteer one's services.
  

(v. i.)
To enter into, or offer for, any service of one's own free will, without solicitation or compulsion; as, he volunteered in that undertaking.
  

(a.)
One who enters into, or offers for, any service of his own free will.
  

(a.)
One who enters into service voluntarily, but who, when in service, is subject to discipline and regulations like other soldiers; -- opposed to conscript; specifically, a voluntary member of the organized militia of a country as distinguished from the standing army.
  

(a.)
Of or pertaining to a volunteer or volunteers; consisting of volunteers; voluntary; as, volunteer companies; volunteer advice.
  

(a.)
A grantee in a voluntary conveyance; one to whom a conveyance is made without valuable consideration; a party, other than a wife or child of the grantor, to whom, or for whose benefit, a voluntary conveyance is made.
  

mao2 sui4 zi4 jian4
Mao Sui recommending himself.
Used to describe a person who volunteers his services for a task or post.