Definition of "Radical" :

noun: (linguistics) the form of a word after all affixes are removed

noun: a character conveying the lexical meaning of a logogram

noun: a person who has radical ideas or opinions

noun: (mathematics) a quantity expressed as the root of another quantity

noun: (chemistry) two or more atoms bound together as a single unit and forming part of a molecule

noun: an atom or group of atoms with at least one unpaired electron; in the body it is usually an oxygen molecule that has lost an electron and will stabilize itself by stealing an electron from a nearby molecule

"In the body free radicals are high-energy particles that ricochet wildly and damage cells."

adjective: especially of leaves; located at the base of a plant or stem; especially arising directly from the root or rootstock or a root-like stem

"Radical leaves."

adjective: (used of opinions and actions) far beyond the norm

"Radical opinions on education."

adjective: markedly new or introducing radical change

"Radical political views."

adjective: arising from or going to the root or source

"A radical flaw in the plan."

adjective: of or relating to or constituting a linguistic root

"A radical verb form."