radical

US /ˈrædɪkəl,'rædɪkḷ/

・

UK /ˈrædɪkl/

A group of atoms behaving as a unit in a chemical compound.
Person who believes in extreme political change
An atom, molecule, or ion that has an unpaired electron and is therefore unstable and highly reactive.
In linguistics, a radical is a basic part of a character, especially in Chinese and other East Asian scripts.
A quantity expressed as the root of another.
A person who advocates thorough or complete political or social reform; a member of a radical party.
The root of a word.

Very new and different from what is traditional
Concerning something's most basic part or form
Relating to or affecting the fundamental nature of something; far-reaching or thorough.
Advocating or based on thorough or complete political or social reform; representing or supporting an extreme section of a political party.