Dictionary/開戦かいせんKaisen開戦 (Kaisen) is a Japanese noun meaning “outbreak of war, starting a war”.Meaningsnoun, suru verb, intransitive verboutbreak of war; starting a warKanji in 開戦開open戦warRelated words開くto open開くto open (e.g. doors)戦うto make war (on)開けるto open (a door, etc.)開けるto open out (of a view, scenery, etc.)戦war開閉opening and shutting作戦tactics開発development戦争war開始start展開development