extremist

[ ik-stree-mist ]
/ ɪkˈstri mɪst /

noun

a person who goes to extremes, especially in political matters.
a supporter or advocate of extreme doctrines or practices.

adjective

belonging or pertaining to extremists.

Origin of extremist

First recorded in 1840–50; extreme + -ist
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for extremist

British Dictionary definitions for extremist

extremist
/ (ɪkˈstriːmɪst) /

noun

a person who favours or resorts to immoderate, uncompromising, or fanatical methods or behaviour, esp in being politically radical

adjective

of, relating to, or characterized by immoderate or excessive actions, opinions, etc

Derived forms of extremist

extremism, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012