radical
adjective
°Favouring fundamental change, or change at the root cause of a matter.
"His beliefs are radical."
°(botany not comparable) Of or pertaining to a root .
noun
°(historical: 19th-century England) A member of the most progressive wing of the Liberal Party; someone favouring social reform (but generally stopping short of socialism).
°(historical: early 20th-century France) A member of an influential, centrist political party favouring moderate social reform, a republican constitution, and secular politics.