戦い【たたかい】
battle, war, fight, conflict, fight (against time, poverty, etc.), struggle (for freedom, survival, etc.), war (e.g. on drugs), battle (e.g. against nature), contest, competition, match, game
作戦【さくせん】
tactics, strategy, military operation, naval operation
戦争【せんそう】
war, fighting, fierce competition
戦う【たたかう】
to make war (on), to wage war (against), to go to war (with), to fight (with), to do battle (against), to compete (against), to struggle (against adversities, etc.), to fight, to contend, to resist
挑戦【ちょうせん】
challenge, defiance, dare, attempt, try
戦闘【せんとう】
battle, fight, combat
戦士【せんし】
soldier, combatant, warrior
戦場【せんじょう】
battlefield, battleground
戦車【せんしゃ】
tank (military vehicle), chariot
戦略【せんりゃく】
strategy, tactics
回戦【かいせん】
event with ... rounds, innings, legs, etc., nth-round match (in a knockout tournament)
対戦【たいせん】
fighting (against), taking on (an opponent), facing, confronting, competing (with), battle, fight, contest, match
決勝戦【けっしょうせん】
championship game, finals (of a tournament), deciding round
挑戦者【ちょうせんしゃ】
challenger
戦力【せんりょく】
war potential, military strength, fighting power, ability (to compete), capabilities, valuable asset
決戦【けっせん】
decisive battle, deciding match, play-off
戦術【せんじゅつ】
tactics
苦戦【くせん】
hard fight, close game, struggle, tight contest
戦後【せんご】
postwar period, period after Second World War
冷戦【れいせん】
cold war, the Cold War