Source : Webster's Revised Unabridged Dictionary (1913)

Affirmation \Af`fir*ma"tion\, n. [L. affirmatio: cf. F.
   affirmation.]
   1. Confirmation of anything established; ratification; as,
      the affirmation of a law. --Hooker.

   2. The act of affirming or asserting as true; assertion; --
      opposed to {negation} or {denial}.

   3. That which is asserted; an assertion; a positive
      statement; an averment; as, an affirmation, by the vender,
      of title to property sold, or of its quality.

   4. (Law) A solemn declaration made under the penalties of
      perjury, by persons who conscientiously decline taking an
      oath, which declaration is in law equivalent to an oath.
      --Bouvier.

Source : WordNet®

affirmation
     n 1: a statement asserting the existence or the truth of
          something [syn: {avowal}, {avouchment}]
     2: the act of affirming or asserting or stating something [syn:
         {assertion}, {statement}]
     3: (religion) a solemn declaration that serves the same purpose
        as an oath (if an oath is objectionable to the person on
        religious or ethical grounds)
     4: a judgment by a higher court that the judgment of a lower
        court was correct and should stand [ant: {reversal}]