Open English Wordnet
Adjectives
(a)decisivedetermining or having the power to determine an outcome“cast the decisive vote”,
“two factors had a decisive influence” (s)decisiveunmistakable“had a decisive lead in the polls” (a)decisivecharacterized by decision and firmness“an able and decisive young woman”,
“we needed decisive leadership”,
“she gave him a decisive answer” (s)critical, decisiveforming or having the nature of a turning point or crisis“a critical point in the campaign”,
“the critical test”