liberal: [14] The Latin word for ‘free’ was līber. It came from the same prehistoric source as Greek eleútheros ‘free’, which may have denoted ‘people, nation’ (in which case the underlying etymological meaning of the word would be ‘being a member of the (free) people’, as opposed to ‘being a slave’). From līber was derived līberālis ‘of freedom’, which passed into English via Old French liberal.
Its earliest English meanings were ‘generous’ and ‘appropriate to the cultural pursuits of a ‘free’ man’ (as in ‘the liberal arts’). The connotations of ‘tolerance’ and ‘lack of prejudice’ did not emerge until the 18th century, and the word’s use as a designation of a particular political party in Britain dates from the early 19th century. Also from Latin līber come English libertine [14] and liberty [14]. => libertine, liberty[liberal etymology, liberal origin, 英语词源]