Adjective
1. determining or having the power to determine an outcome;
"cast the decisive vote""two factors had a decisive influence"2. unmistakable;
"had a decisive lead in the polls"3. characterized by decision and firmness;
"an able an decisive young woman""we needed decisive leadership""she gave him a decisive answer"4. forming or having the nature of a turning point or crisis;
"a critical point in the campaign""the critical test"