Definitive

1. adjective

   supplying or being a final or conclusive settlement

   “a definitive verdict”

   Similar: determinate

2. adjective

   clearly defined or formulated; - R.B.Taney

   “the plain and unequivocal language of the laws”

   Similar: unequivocal

3. adjective

   of recognized authority or excellence

   “the definitive work on Greece”

   Similar: authoritative, classical, classic