definitive in WordNet English dictionary

1. of recognized authority or excellence
   "the definitive work on Greece"; "classical methods of navigation"
   authoritative  classical  classic  definitive 
   
2. supplying or being a final or conclusive settlement
   "a definitive verdict"; "a determinate answer to the problem"
   definitive  determinate 
   
3. clearly defined or formulated
   "the plain and unequivocal language of the laws"- R.B.Taney
   definitive  unequivocal