RADICAL

-adj.
2. thoroughgoing or extreme, esp. as regards change from accepted or traditional forms: a radical change in the policy of a company. 3. favoring drastic political, economic, or social reforms: radical ideas; radical and anarchistic ideologues.
–n.
9. a person who holds or follows strong convictions or extreme principles; extremist.
10. a person who advocates fundamental political, economic, and social reforms by direct and often uncompromising methods.
—Syn.
2. complete, unqualified, thorough; drastic, excessive, immoderate, violent. RADICAL, EXTREME, FANATICAL denote that which goes beyond moderation or even to excess in opinion, belief, action, etc. RADICAL emphasizes the idea of going to the root of a matter, and this often seems immoderate in its thoroughness or completeness: radical ideas; radical changes or reforms. EXTREME applies to excessively biased ideas, intemperate conduct, or repressive legislation: to use extreme measures. FANATICAL is applied to a person who has extravagant views, esp. in matters of religion or morality, which render that person incapable of sound judgments; and excessive zeal which leads him or her to take violent action against those who have differing views: fanatical in persecuting others.