Source : Webster's Revised Unabridged Dictionary (1913)

Presumption \Pre*sump"tion\ (?; 215), n. [L. praesumptio: cf. F.
   pr['e]somption, OF. also presumpcion. See {Presume}.]
   1. The act of presuming, or believing upon probable evidence;
      the act of assuming or taking for granted; belief upon
      incomplete proof.

   2. Ground for presuming; evidence probable, but not
      conclusive; strong probability; reasonable supposition;
      as, the presumption is that an event has taken place.

   3. That which is presumed or assumed; that which is supposed
      or believed to be real or true, on evidence that is
      probable but not conclusive. ``In contradiction to these
      very plausible presumptions.'' --De Quincey.

   4. The act of venturing beyond due beyond due bounds; an
      overstepping of the bounds of reverence, respect, or
      courtesy; forward, overconfident, or arrogant opinion or
      conduct; presumptuousness; arrogance; effrontery.

            Thy son I killed for his presumption. --Shak.

            I had the presumption to dedicate to you a very
            unfinished piece.                     --Dryden.

   {Conclusive presumption}. See under {Conclusive}.

   {Presumption of fact} (Law), an argument of a fact from a
      fact; an inference as to the existence of one fact not
      certainly known, from the existence of some other fact
      known or proved, founded on a previous experience of their
      connection; supposition of the truth or real existence of
      something, without direct or positive proof of the fact,
      but grounded on circumstantial or probable evidence which
      entitles it to belief. --Burrill. --Best. --Wharton.

   {Presumption of law} (Law), a postulate applied in advance to
      all cases of a particular class; e. g., the presumption of
      innocence and of regularity of records. Such a presumption
      is rebuttable or irrebuttable.

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}.