(in the past 旧时 a formal fight with weapons between two people who disagreed, especially over a matter of honour （旧时为解决纷争的）决斗 to fight/win a duel 进行／赢得决斗 to challenge somebody to a duel 要求与某人决斗
Extra ExamplesHe fought a duel with the prince. 他与王子决斗。 a duel between the two officers 两名军官之间的决斗
a competition or struggle between two people or groups （双方的）竞争，斗争 The debate rapidly descended into a verbal duel between the two candidates. 辩论迅速演变成两位候选人之间的口头对决。
Word Originlate 15th cent.: from Latin duellum, archaic and literary form of bellum ‘war’, used in medieval Latin with the meaning ‘combat between two persons’, partly influenced by dualis ‘of two’. The original sense was ‘single combat used to decide a judicial dispute’; the sense ‘contest to decide a point of honour’ dates from the early 17th cent.