de·ci·sive 
(dĭ-sīsĭv)
(dĭ-sīsĭv)adj.
1. Settling a matter or conflict; conclusive: the decisive battle in the war; the decisive piece of evidence in the lawsuit.
2. Characterized by or showing the ability to make decisions quickly and firmly; resolute: a decisive leader.
de·cisive·ly adv.
de·cisive·ness n.
Synonyms: decisive, conclusive, critical, crucial, definitive, determinative
These adjectives mean determining an outcome or settling an issue with finality: the decisive vote; a conclusive reason; a critical experiment; a crucial moment; a definitive verdict; the determinative battle.
These adjectives mean determining an outcome or settling an issue with finality: the decisive vote; a conclusive reason; a critical experiment; a crucial moment; a definitive verdict; the determinative battle.
Antonym: indecisive