Source : Webster's Revised Unabridged Dictionary (1913)

Effectualness \Ef*fec"tu*al*ness\, n.
   The quality of being effectual.

Source : WordNet®

effectualness
     n : power to be effective; the quality of being able to bring
         about an effect [syn: {effectiveness}, {effectivity}, {effectuality}]
         [ant: {ineffectiveness}]