Adjectives

(s)definitive, unequivocalclearly defined or formulated“the plain and unequivocal language of the laws” (R.B.Taney)
(s)authoritative, definitiveof recognized authority or excellence“the definitive work on Greece”
(s)definitive, determinatesupplying or being a final or conclusive settlement“a definitive verdict”, “a determinate answer to the problem”