volunteer in WordNet English dictionary

1. (military) a person who freely enlists for service
   volunteer  military volunteer  voluntary 
   
2. a person who performs voluntary work
   volunteer  unpaid worker 
   

1. 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"
   volunteer  offer 
   
2. tell voluntarily
   "He volunteered the information"
   volunteer 
   
3. do volunteer work
   volunteer 
   

1. without payment
   "the soup kitchen was run primarily by unpaid helpers"; "a volunteer fire department"
   unpaid  volunteer