noun, noun which may take the genitive case particle 'no'
Political ideology advocating a republican form of government, where the head of state is not a monarch.
彼は共和主義の理念を強く支持している。
He strongly supports the ideals of republicanism.
共和主義的な改革
Republican reforms are being discussed.
Compound of 共和 (きょうわ, 'republic') + 主義 (しゅぎ, '-ism'). 共和 is a Meiji-era coinage from Chinese 共和, originally meaning 'joint harmony' and used to translate 'republic'.