A computer program product of decision definition using a rules vocabulary includes program code for: receiving free form input; identifying terms contained within the free form input; searching the rules vocabulary objects for terms; responsive to the term being found, obtaining input from a user as to whether to use the found term; responsive to the term not being found; searching the rules vocabulary attributes for terms having attributes corresponding to the term; responsive to the term being found, obtaining input from a user as to whether to use the found term; and refactoring the free form input with the found term accepted by the user. The program code also includes code for updating the rules vocabulary with the term identified in the free form input as a synonym for the term found in said rules vocabulary. One embodiment further provides determining semantic equivalence between a plurality of rules using a rules database having preferred terms.