Decisive 是一个与熟词 decide 同源的单词，该词源自拉丁语decidere（切断；决定），1584年经中古拉丁语decisivus进入英语后即用来表示“决定性的、具有决定意义的、关键的”，主要指能够解决某个问题、争论以及任何不确定的事物，产生一个确定的结果，或者说对某个特定情况的最终结果至关重要，

比如：

After losing this decisive battle, the extreme and strident minister of defense superseded his feeble boss as president.输掉了这场决定性的战役后，这位极端且强硬的国防部长取代他软弱的上司担任总统。

She has played a decisive role in the peace negotiations. The proposal imbued with the spirit of peace has been embodied in a draft resolution.她在和谈中起了关键作用。那项充满和平精神的提案包含在了决议草案中。

The feud has been smouldering on for years. You need to be more decisive.从这个概念出发， decisive 很自然地就被用来引申形容人或行动等“果断的、决断的”，也就是有能力在困难或复杂情况下快速且自信地决定某事的，比如：多年来，这场冤仇一直在积结。你要更果断一些。

Presidents with strong nerves are decisive. They don't balk at unpopular decisions.名人用例

conclusive: (of evidence or argument) serving to prove a case; decisive or convincing pivotal: of crucial importance in relation to the development or success of something else crucial: decisive or critical, especially in the success or failure of something有着强大魄力的总统处事果敢。他们不会对不受欢迎的决定犹豫不决。出自美国知名记者、政治评论员弗雷德·巴恩斯（Fred Barnes）。同近义词