decisive

adjective

1. 1

   forming or having the nature of a turning point or crisis

   a critical point in the campaign

   the critical test

2. 2

   determining or having the power to determine an outcome

   cast the decisive vote

   two factors had a decisive influence

3. 3

   characterized by decision and firmness

   an able and decisive young woman

   we needed decisive leadership

4. 4

   unmistakable

   had a decisive lead in the polls