libertarian

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One who advocates maximizing individual rights and minimizing the role of the state.
2. n. One who believes in free will.

Century Dictionary and Cyclopedia

1. Of or pertaining to liberty, or to the doctrine of the freedom of the will (especially in an extreme form), as opposed to the doctrine of necessity; advocating the doctrine of free will: opposed to necessitarian.
2. n. One who maintains the doctrine of the freedom of the will (especially in an extreme form): opposed to necessitarian.

Wiktionary

1. n. One who advocates liberty either generally or on a specific issue, e.g. "civil libertarian" (in favour of civil liberties).
2. n. A believer in a political doctrine that emphasizes individual liberty and a lack of governmental regulation and oversight both in matters of the economy ('free market') and in personal behavior where no one's rights are being violated or threatened. Also 'classical liberal', akin to 'anarcho-capitalist'.
3. n. An anarchist, typically with socialist implications.
4. n. philosophy A believer in thinking beings' freedom to choose their own destiny, i.e. a believer in free will as opposed to those who believe the future is predetermined.
5. n. US, prefixed to "Republican" a member of the Republican Party (especially a legislator) who emphasizes economic and Constitutional, rather than religious and personal, aspects of the party's platform.
6. adj. Having the beliefs of libertarians; a relative tendency towards liberty.

GNU Webster's 1913

1. adj. Pertaining to liberty, or to the doctrine of free will, as opposed to the doctrine of necessity.
2. n. One who holds to the doctrine of free will.

WordNet 3.0

1. n. an advocate of libertarianism
2. n. someone who believes the doctrine of free will