decisive

形容词 decisive:

1. determining or having the power to determine an outcome
2. unmistakable
3. characterized by decision and firmness
4. forming or having the nature of a turning point or crisis
   同义词：critical

1. The report brought about a decisive change in the whole policy.
   这个报告使整个方针发生了决定性的变化。
2. The enemy was defeated in a decisive battle.
   敌人在一场决定性的战斗中被击败。
3. Be decisive, tell them exactly what you think should be done.
   果断些，确切地告诉他们你认为应该怎么做。
4. The injury to their key player could be a decisive factor in the game.
   他们主力队员受伤可能是这场比赛胜负的决定性因素。

de.ci.sive

adj.（形容词）
Having the power to decide; conclusive.
决定性的：有权决定的；结论性的
Characterized by decision and firmness; resolute.
决断的：具有果断坚决的特征的；坚定的
Beyond doubt; unmistakable:
明确的：毫无疑问的；无误的：
例句：
a decisive defeat.
确实无疑的失败

【引伸】
deci.sively
adv.（副词）
deci.siveness
n.（名词）
<参考词汇><同义词>decisive,conclusive,crucial,definitive,determinativeThe central meaning shared by these adjectives is .determining or having the power to determine an outcome.:
这些形容词共同的中心的含义是"决定性的，有权决定结果的"：
例句：
the decisive vote;
决定性的一票；

例句：
a conclusive reason;
决定性的理由；

例句：
crucial experiments;
关键的实验；

例句：
a definitive verdict;
明确的裁决；

例句：
the determinative battle. indecisive
决定性的战役 indecisive