Source : Webster's Revised Unabridged Dictionary (1913)

Excellence \Ex"cel*lence\, n. [F. excellence, L. excellentia.]
   1. The quality of being excellent; state of possessing good
      qualities in an eminent degree; exalted merit; superiority
      in virtue.

            Consider first that great Or bright infers not
            excellence.                           --Milton.

   2. An excellent or valuable quality; that by which any one
      excels or is eminent; a virtue.

            With every excellence refined.        --Beattie.

   3. A title of honor or respect; -- more common in the form
      excellency.

            I do greet your excellence With letters of
            commission from the king.             --Shak.

   Syn: Superiority; pre["e]minence; perfection; worth;
        goodness; purity; greatness.

Source : WordNet®

excellence
     n 1: the quality of excelling; possessing good qualities in high
          degree
     2: something in which something or some one excels; "the use of
        herbs is one of the excellences of French cuisine"