One who advocates liberty, either generally or in relation to a specific issue.
(chiefly US) A believer in a political doctrine that emphasizes individual liberty and a lack of governmental regulation, intervention, 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, a ‘classical liberal’, akin to an ‘anarcho-capitalist’.
(chiefly Britain, Ireland) A left-libertarian, an antiauthoritarian believer in both individual freedom and social justice (social equality and mutual aid), such as a social anarchist.
(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.
(philosophy) A political philosophy maintaining that all persons are the absolute owners of their own lives, and should be free to do whatever they wish with their persons or property, provided they allow others that same liberty.