Volunteer

Part of speech: noun (n.)

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

2. 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. 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.

Part of speech: verb (v.)

To offer or bestow voluntarily, or without solicitation or compulsion; as, to volunteer one's services.

Part of speech: verb (v.)

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

Part of speech: adjective (a.)

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