To Volunteer

1. (intransitive) To enlist oneself as a volunteer.
2. (transitive, intransitive) To do or offer to do something voluntarily.
3. (transitive) To offer, usually unprompted.
4. (intransitive, botany) To grow without human sowing or intentional cultivation.
5. (transitive, informal) To offer the services of (someone else) to do something.