Source : Webster's Revised Unabridged Dictionary (1913)

Intentness \In*tent"ness\, n.
   The state or quality of being intent; close application;
   attention.

         Extreme solicitude or intentness upon business.
                                                  --South.

Source : WordNet®

intentness
     n : the quality of being intent and concentrated; "the
         intentness of his gaze" [syn: {engrossment}]