Definitions
1.AdjectiveHaving the power or quality of deciding a question or controversy; putting an end to contest or controversy; final; conclusive."decisive vote; decisive battle"
2.AdjectiveDecided; definite; incontrovertible."decisive victory"
3.AdjectiveMarked by promptness and decision, resolute; without hesitation."decisive action; a decisive person"
4.Adjective↑ Hurd, Seth P. (1847), “Decisive”, in “False Pronunciation”, in A Grammatical Corrector; or, A Vocabulary of the Common Errors of Speech, Philadelphia: E. H. Butler & Co, →OCLC, page 80.