noun
Refers to a political ideology advocating fundamental or extreme change, often used in historical or ideological contexts.
19世紀の急進主義は、普通選挙権を求めた。
19th-century radicalism demanded universal suffrage.
過激主義 implies more extreme, often violent methods, while 急進主義 focuses on rapid, fundamental change without necessarily implying violence.
Compound of 急進 (rapid progress) and 主義 (principle, -ism). The term is a calque from Western political vocabulary.