Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
signĭfĭcātīvus, a, um, adj. [significo], denoting, signifying, significative (jurid. Lat.); with gen.: enuntiatio et quantitatis et aestimationis significativa, Dig. 50, 16, 232; 45, 1, 75, § 2.