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