How to say "communism" in Japanese

• 共産きょうさんJLPT N1approx.Common
  nounNot really the word you want when referring to communism as an ideology; it does not stand alone as a noun for the doctrine. It functions mainly as a stem within related expressions, so learners should normally reach for 共産主義 instead.
• 共産主義きょうさんしゅぎCommon
  nounThis is the full term for communism as a political ideology or doctrine, and the natural choice when discussing the ideology itself, its principles, or its history. When you mean 'communism' in ordinary talk or writing, this is the word to use.
  アメリカ人あめりかじんがファシズムを受け入うけいれないのは、共産主義きょうさんしゅぎを受け入うけいれないのと同おなじだ。↗

  The Americans don't accept Fascism any more than they do Communism.

For the ideology 'communism' itself, use 共産主義; 共産 is not a standalone word for the doctrine but a stem used inside related terms, so choose 共産主義 unless you specifically need that combining element.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 共産きょうさんcommunism
• 共産主義きょうさんしゅぎcommunism
• コミュニズムcommunism