Source : Webster's Revised Unabridged Dictionary (1913)

Volunteer \Vol`un*teer"\, n. [F. volontaire. See {Voluntary},
   a.]
   1. One who enters into, or offers for, any service of his own
      free will.

   2. (Mil.) 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.

   3. (Law) 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.
      --Burrill.

Volunteer \Vol`un*teer"\, a.
   Of or pertaining to a volunteer or volunteers; consisting of
   volunteers; voluntary; as, volunteer companies; volunteer
   advice.

Volunteer \Vol`un*teer"\, v. t. [imp. & p. p. {Volunteered}; p.
   pr. & vb. n. {Volunteering}.]
   To offer or bestow voluntarily, or without solicitation or
   compulsion; as, to volunteer one's services.

Volunteer \Vol`un*teer"\, 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.

Source : WordNet®

volunteer
     v 1: tell voluntarily; "He volunteered the information"
     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" [syn: {offer}]
     3: do volunteer work

volunteer
     adj : without payment; "the soup kitchen was run primarily by
           unpaid helpers"; "a volunteer fire department" [syn: {unpaid},
            {volunteer(a)}]
     n 1: (military) a person who freely enlists for service [syn: {military
          volunteer}, {voluntary}] [ant: {draftee}]
     2: a person who performs voluntary work [syn: {unpaid worker}]