An extremist, in the current parlance, is someone who disagrees with "modern society": the combination of industrial capitalism and personal liberty in democratic systems that defines the progressive West. All of Europe and North America and most of their allies have some variation on this type of system. Even further, it is upheld as the reason to support the West in its crusades: we bring you "freedom" and a nifty product-oriented lifestyle. However, such modern society is by definition very popular, because it tells everyone they are liable only to themselves and their own interests, and that there is need for no other social involvement. Do what benefits you personally, both materially and in social status. Most people do not understand why anyone would oppose this, thus "extremists" tend to work through that form of guerrilla warfare native to our time, sometimes called "terrorism." What is Extremism and Why It's Our Only Hope
So, an extremist could also be someone who disagrees with "modern extremism": the combination of abhorance of industrial capitalism and personal liberty in democratic systems that defines the progressive West? Or is an extremist someone who imagines oneself to be more special than everyone else in "modern society" in abhorance of personally lacking actual ability to successfully compete with most other people on a level playing field?
That's just a contemporary co-opting of the term by those in power. Extremism means any direction. Barry Goldwater, who would hardly be called an "extremist" by this year's newsvermin, called himself one: "Extremism in the pursuit of liberty is no vice."
Extremism is not politically correct because 'difference' is not politically correct. Wherever there are scales and spectrums there will be inequality and discrimination...and rightfully so. Extremism simply means being at one end or the other of a spectrum. The grand ideal of political correctness is to have one flat level playing field of sameness.
Sounds boring -- one flat level for everyone? The only person who would like that would be someone who was afraid they were inferior.
or perhaps someone that believes in giving everyone the same opportunities, regardless of seemingly random qualities that seperate us in our ideologies.