Source : Webster's Revised Unabridged Dictionary (1913)

Picturesque \Pic`tur*esque"\, a. [It. pittoresco: cf. F.
   pittoresque. See {Pictorial}.]
   Forming, or fitted to form, a good or pleasing picture;
   representing with the clearness or ideal beauty appropriate
   to a picture; expressing that peculiar kind of beauty which
   is agreeable in a picture, natural or artificial; graphic;
   vivid; as, a picturesque scene or attitude; picturesque
   language.

         What is picturesque as placed in relation to the
         beautiful and the sublime? It is . . . the
         characteristic pushed into a sensible excess. --De
   Quincey. -- {Pic`tur*esque"ly}, adv. -- {Pic`tur*esque"ness},
   n.

Source : WordNet®

picturesqueness
     n : visually vivid and pleasing