determinative

Adjective

• having the power or quality of deciding
  • the crucial experiment
    
  • cast the deciding vote
    
  • the determinative (or determinant) battle
    

Noun

• a determining or causal element or factor
  • education is an important determinant of one's outlook on life
    

• one of a limited class of noun modifiers that determine the referents of noun phrases

Related words

• Synonyms: 
  deciding(a) , determinant , determining(a) , determiner , determining factor , causal factor