whats A "radical"?

Answer 1

Someone who thinks for themselves and tries to come up with solutions outside the accepted realm.

Answer 2

It's a mathmatical term to describe the sum of a decending sequence of integers, using an exclamation mark (!) as it's notation. The Radical of 5 (written 5!) is 15, because 5+4+3+2+1=15.
8!=8+7+6+5+4+3+2+1=36

Answer 3

A radical is someone who is at the extreme end of a belief. So much so that they cannot possibly see the point of view of anyone else. Sometimes they are violent in their beliefs. American Nazis advocate such violence. The KKK was a radical group when it came to race and religion. Most people are referred to as mainstream. They are what is normal. They generally are in the middle of opinion in a conflict of ideas. Radicals are on the very ends and usually don't listen nor do they care about someone else's opinion. Often radicals call their opponents, even those ever slightly in the opposite direction horrible names and epithets. They often lie to make their point. Why people are like that generally stems from ego. They can't stand to have anyone even think they could be wrong. One could call it uber ego.

Answer 4

Someone with political views that are an extreme position.

It is very much a label that depends on the society that evaluates it.

For example: 'radical abolitionists' wanted to free the slaves

Answer 5

some mathematic term

Answer 6

Here, read for yourself.