Radical has the following definitions: “(1) Relating to or affecting the fundamental nature of something; far-reaching or thorough. (2) Advocating or based on thorough or complete political or social reform; representing or supporting an extreme section of a political party. (3) A person who advocates thorough or complete political or social reform; a member of a political party or part of a party pursuing such aims. (4) A group of atoms behaving as a unit in a number of compounds.

Radicle is defined as following: (1) A rootlike subdivision of a nerve or vein. (2) The part of a plant embryo that develops into the primary root.