Source : Webster's Revised Unabridged Dictionary (1913)

Activeness \Ac"tive*ness\, n.
   The quality of being active; nimbleness; quickness of motion;
   activity.

Source : WordNet®

activeness
     n 1: the state of being active; "his sphere of activity"; "he is
          out of action" [syn: {action}, {activity}] [ant: {inaction},
           {inaction}, {inaction}]
     2: the trait of being active; moving or acting rapidly and
        energetically; "the level of activity declines with age"
        [syn: {activity}] [ant: {inactiveness}]