Fangen wir mit der Belegsammlung mal mit einem Anwendungsbeispiel an :
https://www.thefreedictionary.com/extremist
... extremist
noun
1. radical, activist, militant, enthusiast, fanatic, devotee, die-hard, bigot, zealot, energumen Police believe
the bombing was the work of left-wing extremists.
... Collins Thesaurus of the English Language – Complete and Unabridged 2nd Edition. 2002 © HarperCollins Publishers 1995, 2002