Source : Webster's Revised Unabridged Dictionary (1913)

Desirableness \De*sir"a*ble*ness\, n.
   The quality of being desirable.

         The desirableness of the Austrian alliance. --Froude.

Source : WordNet®

desirableness
     n 1: the quality of being worthy of desiring [syn: {desirability}]
          [ant: {undesirability}]
     2: attractiveness to the opposite sex [syn: {sex appeal}, {desirability},
         {oomph}]