In politics, anyone with opinions more extreme than the main current of a country's major political party or parties. It is more often applied to those with left-wing opinions, although the radical right also exists.1. A character conveying the lexical meaning of a logogram.
2. A person who has radical ideas or opinions.
3. A sign placed in front of an expression to denote that a root is to be extracted; SYN. radical sign.
In Britain, supporter of parliamentary reform before the Reform Bill 1832. As a group the Radicals later became the progressive wing of the Liberal Party. During the 1860s (led by Cobden, Bright, and J S Mill) they campaigned for extension of the franchise, free trade, and laissez faire, but after 1870, under the leadership of Joseph Chamberlain and Charles Dilke, they adopted a republican and semisocialist program. With the growth of socialism in the later 19th century, Radicalism ceased to exist as an organized movement.
In France, the Radical Party was a major force in the politics of the Third Republic, 1871–1940.