Source : Webster's Revised Unabridged Dictionary (1913)

Amiability \A`mi*a*bil"i*ty\, n.
   The quality of being amiable; amiableness; sweetness of
   disposition.

         Every excellency is a degree of amiability. --Jer.
                                                  Taylor.

Source : WordNet®

amiability
     n 1: a cheerful and agreeable mood [syn: {good humor}, {good
          humour}, {good temper}] [ant: {ill humor}]
     2: a disposition to be friendly and approachable (easy to talk
        to) [syn: {affability}, {affableness}, {amiableness}, {bonhomie},
         {geniality}]