determinative
     adj : having the power or quality of deciding; "the crucial
           experiment"; "cast the deciding vote"; "the
           determinative (or determinant) battle" [syn: {crucial},
            {deciding(a)}, {determinant}, {determining(a)}]
     n 1: one of a limited class of noun modifiers that determine the
          referents of noun phrases [syn: {determiner}]
     2: a determining or causal element or factor; "education is an
        important determinant of one's outlook on life" [syn: {determinant},
         {determiner}, {determining factor}, {causal factor}]
Source: WordNet® 2.0