1 [intransitive and transitive]
to offer to do something without expecting any reward, often something that other people do not want to do
volunteer to do something
Helen volunteered to have Thanksgiving at her house this year.
Sidcup volunteered for guard duty.
I volunteered my services as a driver.
to tell someone something without being asked:
Michael volunteered the information before I had a chance to ask.
to offer to join the army, navy, or airforce:
When war broke out, my father volunteered immediately.
to say that someone else will do a job even though they may not want to do it
volunteer somebody for something
Mum volunteered Dave for washing-up duties.