noun
reactionism
Political ideology opposing progressive change and seeking to restore a previous state of affairs.
彼の主張は反動主義だと批判された。
His argument was criticized as reactionism.
反動 is the broader term for 'reaction' or 'backlash', while 反動主義 specifically denotes the ideology of reactionism.
Compound of 反動 (reaction) and 主義 (principle, -ism), likely a calque from Western political terminology.