A radical is a person subscribing to a political ideology supporting massive, unmeasured, and rapid change. Radicalism is contrasted with conservatism that advocate minimum change, reactionary action advocating counter-change, as well as progressivism advocating moderate/measured change.
A radical would want to chang, for example, a feudal system into a completely capitalist system, or a completely capitalist system into a communist one. Another exaple of radicalism would be a person who wanted to change an Islamic Theocracy into an Atheist state (see en.wikipedia.org/wiki/state_atheism)!
Radical (rahd eek al) is a word used proficiently and often by Michaelangelo of the Teenage Mutant Ninja Turtles. He is the only one on earth that truly knows its awesomeness, although such scholars as William Preston-Esquire and Theordore Theordore Logan have come close to unveiling the true natures of such speak. The best reason for dividing radical is to make more mini-radicals influence from the beinning radical, in hopes of creating a little radical for everyone. And pizza.