1. having the power to decide an outcome; conclusive
2. showing the ability to make decisions quickly and effectively

Examples

• The final goal was decisive in winning the championship.
• Her decisive leadership helped the company through the crisis.
• The evidence was decisive in proving his innocence.
• He made a decisive move to end the argument.
• The battle was decisive in determining the war’s outcome.
• She gave a decisive answer without hesitation.
• The decisive factor was the weather conditions.