How to say "imperialism" in Japanese

• 帝国主義ていこくしゅぎCommon
  no-adjectiveThe direct equivalent for imperialism as an ideology or policy of extending a country's power through expansion and domination; the word you want in historical and political discussion.
• 帝政ていせいCommon
  no-adjectiveChiefly means imperial government or monarchical rule — a state ruled by an emperor. Its 'imperialism' gloss covers this imperial system of rule, not the expansionist ideology; for that sense use 帝国主義.

Use 帝国主義 for imperialism as an ideology or policy of expansion and domination; 帝政 means imperial government or monarchical rule, and matches 'imperialism' only in that governmental sense.

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

• 帝国主義ていこくしゅぎimperialism
• 帝政ていせいimperial government
• インペリアリズムimperialism