Source : Webster's Revised Unabridged Dictionary (1913)

Conclusive \Con*clu"sive\, a. [Cf. F. conclusif.]
   Belonging to a close or termination; decisive; convincing;
   putting an end to debate or question; leading to, or
   involving, a conclusion or decision.

         Secret reasons . . . equally conclusive for us as they
         were for them.                           --Rogers.

   {Conclusive evidence} (Law), that of which, from its nature,
      the law allows no contradiction or explanation.

   {Conclusive presumption} (Law), an inference which the law
      makes so peremptorily that it will not allow it to be
      overthrown by any contrary proof, however strong.

   Syn: Final; ultimate; unanswerable. See {Final}.

Source : WordNet®

conclusive
     adj 1: forming an end or termination; especially putting an end to
            doubt or question; "conclusive proof"; "the evidence
            is conclusive" [ant: {inconclusive}]
     2: final and deciding; "the conclusive reason"
     3: expressing finality with no implication of possible change;
        "an absolute (or unequivocal) quarantee to respect the
        nation's authority"; "inability to make a conclusive (or
        unequivocal) refusal" [syn: {absolute}]